Speed is slower in FFH 2 (officially on purpose).
Expect it to play like one speed bump slower than vanilla.
Also very important to note: Experience / Promotions are far more important than in Vanilla (usually double the effect) + the base power of most units in the early stages of the game up to early midgame is more drawn out (in your game that might be until ~ Turn 350) so the power of your units is more down to battle-hardened they are. That might be a much bigger factor than the difference between Axemen and Warriors. Warriors are rather powerful for a rather long time in FFH2 compared to vanilla. No better offensive units than Warriors for the first 100 Turns or so is very possible in a game of normal speed. And while not really good you might still survive with a big force of warriors until around turn 200 allright. At least on the lower difficulties.
Also the early game is designed to give more time to play with the "new tools" so be-lining into military does pay off in that your Axemen / Hunters / Horsemen will be quite good for quite some time to come.
It has been smothened a bit! in the most recent patches but its still like it should be.
If you really dislike the slower pace switch to quick allright. (and stay the hell away from marathon unless you absolutely love games spanning days if not weeks. Epic more than enough provides for long games. And normal should be comparable to a good epic session of vanilla)
All in all for one of your first games and provided you are isolated you seem to do quite well
. (No need to do really good on your first few tries, given how fast you seem to grasp things that'll come to pass fast enough... Also don't hesitate to go up in difficulty a notch or two if the AI proves to low of a challenge. A direct comparison to BtS-difficulty will not really be helpful. Don't shy away from monarch or even emperor when you squash / dominate the AI time after time... Immortal and up still is quite demanding but for many players the jump to Monarch / Emperor comes sooner or later.)
Economy: Some things are key to keeping your science-slider up.
Early game: Getting markets from festivals tech helps very much (running merchants and settling great merchants if you get one / some might also help.), cheap and effective.
If at peace city states civic (from cartography, government category) works wonders. (Aristocracy might help as well and is not so problematic in war but will take some consideration because it makes Farms less effective in terms of food-production.)
Running pacifism civic (one of 3 starting possibilities, social values category) is very expensive in terms of upkeep so you might want to consider switching to Religion or Nationalism or whatever else suits your fancy. (Its actually a fairly weak civic overall and is not really advisable to people new to the mod)
You founded a religion if i spot that rightly (Empyrean) so as in Vanilla building a shrine with a great prophet and spreading your religion liberally will sure help.
Small empires might win just as well as large ones do. That is very much down to civ / settings and strategy. On overall tendency if you can handle large-scale-empire micromanagement in vanilla very well you might likely get along well with that in FFH 2 as well. Otherwise you might want to stick to a smaller one.
But monitor your civic-choices and your choice of civ + abilities and preferences very much
(God-King civic is a godsend for very small empires for example. Large ones might rather want to stick to city-states instead...).
Quite a number of civs here has advantage from smaller / larger empires (Kuoritates / Calabim under Flauros might be good examples of civs strongly favoring one above the other.
And on mapscripts: downright starting with Erebus might prove tricky. (by all means at least set sea-level to low. Then the naval part becomes a bit less of a hassle.). Cephalo still works on that script and may one day make sure at least as an option that connection via Land is guaranteed. So don't expect it to work without any problems / imbalance just yet.
Also on Erebus-maps its advisable to overpopulate a bit (1-3 additional civs compared to your usual number of civs provides a better experience usually.)
If you like warmongering play Lakes or Pangea allright.
Otherwise you might want to stick to continents or other Scripts you did like in Vanilla (usually a decent idea anyways.).
On terraforming:
Small-scale is possible quite early (As mentioned mountains can never be terraformed. That's down to the civ 4-engine and how it handles peaks i believe.)
Spring (The spell you can have your Adepts cast when having Water-Mana after you promote one to the Water I sphere-promotion) turns deserts (without Floodplains feature!) into plains (and is thus very useful if you settle in desert-heavy terrain.). Just move your adept on a desert tile and cast the spell with it. (trying the Gift of Kylorin Scenario gives a neat insight into spellcasting. It might be a good tutorial if you want to learn how to terraform...)
Scorch (The spell you can have your Adepts cast when having Sun-Mana after you promote one to the Sun I sphere-promotion) turns Plains into Deserts. So it might be useful to lay traps for incoming invaders / barbarians.
It also turns Ice-Tiles into tundra. Which might make it a bit helpful (surely not stellar though) if you have a city to hook up some resources in colder pastures and want to beef up the terrain a bit. (It might also help to terrorize some enemies by turning their terrain into plains. I'm not utterly sure right now if you can cast it in enemy territory though.)
Blaze (Spell gained by Fire 1 Promotion) can be used to burn down jungels which regrow as forests afterwards as a possible substitute for chopping them (proceed with caution though! Forest fires do spread.) which will take some time.
Raging forest-fires can be put out by an Adept casting Spring (Water 1 Spell) right next to the burning Tile.
Some time during the game hell terrain may spread on Erebus if bad things happen in the game (thats actually quite bad for most civs. There are a few exceptions though.)
Here the Life 1 Promotion (Sanctify spell) might help to turn hell back into normal terrain.
The real deal with terraforming though comes actually very late into the game.
At Druids / Archmages (for Archmages you'll also need Nature-Mana hooked up) both need to be Promoted to Nature 1+2+3 (so 3 Promotions needed or 2 for Druids because they allready start with nature 1) to learn the Vitalize Spell (and end-game techs as well with Commune with Nature and Strenght of Will respectively) which turns most terrain into Grassland gradually
(so Ice ---> Tundra, Tundra/Desert---> Plains Plains ----> Grassland, also works on Deserts with Floodplains unlike Spring which will produce superb tiles.).
Then there is also Snowfall (Which is mostly just available to Illian civilization. The followers of the God of Winter) which will turn terrain cold (temporarily?) and Temples of the Hand (Illian substitute for Pagan Temples) which turn all the cities fat cross into Ice (permanently).
Another if completely unreliable way to perform some terraforming is Wonder (Spell gained Chaos 3 Promotion) which casts multiple random effects. Including some which turn surrounding terrain into hell-terrain and also possibly the other terrain-modifying effects. Just listed here for sake of completeness. Use for purposeful terraforming not reccomended. (unless you really love hell breaking loose of course.
)
If i remember rightly that's all what can be said about terraforming in FFH 2.
PS: Also count me in with Mesix that the Elves (Arendel, Amelanchier, Thessa and Faeryl) should give a good experience for starters, with them you can just build your improvements in forested tiles instead of having to chop them.
The Ljosalfar focus a bit more on Archery-Line (of techs and units) and turteling / defense,
The Svartalfar are a bit more offensive and favor the recon line and to a lesser degree the arcane line (of techs and units.)
Overall the elves both are rock-solid and easy-to-play civs for builders. (Religionwise Fellowship of Leaves from Way of the Forests tech is very! advisable for both of them. At least until you really get a grip on them. But usually ever.)
As well as the Hippus (especially under Tasunke) if you like Warmongering very much (just focus on the mounted line with them very much, they have terrifying cavalry...).
(Rohanna might do a tad better for you than Tasunke if you like an amalgam of strong Warmongering and building + conquering big empires. Financial trait is a godsend for getting that maintenance covered. Just like it is in Vanilla.)
A very interesting thing to know from you in turn would be how well you can handle the Doviello (after grasping the very basics with whatever civ you fancy. At your leisure of course.
) / how easy they are really play from a vanilla-players perspective.
It's quite often advertised as a good civ for starters (when lead by Mahla, Stay away from Chardaron though, that one downright sucks imo) but i have my serious doubts about that one.
But my perspective could be radically wrong (i will sure be not completely convinced by just a single voice, but each insight is worth it) and since i also try to spread the word about FFH2 here and there + give some helpful tips for a start (possibly to players who are not so much into forums) an unbiased perspective might prove quite helpful to give good advice in the future.