Noob immortal questions

I have won as Poland and Shoshone and dropped the game around 200 turns with India Rome and Sweden. I have played prob 4-5 games non immortal. This is just my impression so far.

Tall vs wide
How can tall ever compare? Wide is so insanely better and likewise tradition is great... Liberty insanely better.

What is tall? 4ish cities? Wide is 6 and up? Once you get all the insane amounts of happiness from ideologies you can have like 12 cities!

How could tall possibly compete with that?

Gats
Is there any point to having archers from gats on? With my last game I just started giving them away... Same with lancers now that I think about it. Useless

Is the a list of people who backstab and those who don't? It's pretty getting back stabbed with no contested borders and nothing making them angry.

Japan and Greece are always going to be the first civs I focus, ass holes.

Is there any honor in winning a dip victory? Seems really easy. It's like oh man I wanted a science game but lemmi just spend 8k gold and auto win, what?

On that note, is cult win even possible?

I'm sure I have more but gotta get back to work.

Thank you for any advice or even links to posts I should read.

It sounds like you have mastered "Wide" but don't know how to play Tall.
Mine is the opposite, I have mastered "Tall" on Immortal but don't know how to play Self Founded Wide.

Tall is 4 self founded cities (or few) with Tradition. If you've only founded 4 cities but went Liberty (or Piety), that is NOT tall as the cities won't possibly grow big enough to be considered tall without the growth bonuses from completing Tradition.
Obviously only self founding 4 cites with Liberty isn't wide either, so with none of the benefits from either it doesn't work well.

You can though have a Tall core empire (4 empire) and attach a wide empire to it via conquest.

Pure Tall is competitive because National Wonders are so powerful. Science tactics are all about getting NC as soon as possible and so prior to BNW most common with 2 city NC on Immortal. BNW removal of ultra early gold sources has more 3 city NC also popular. (Either way the NC is followed up quickly by the final self built cities to bring up to 4 cities.)
But Heroic Epic, Circus Maximums, East India, and Iron Works are also very powerful. Once you start one of these, you tend to want to build all of them and by the time they are all complete it's kind of late to be self founding any more cities.
Especially because by then if you want more, you can just conquer some of the AIs, initially puppet until it won't interfere with national wonder.

Monarchy within Tradition is the most powerful social policy in the game, it removes 50% of the population unhappiness from the capital. Going peaceful it comes close to solving all happiness problems by itself, if attaching a wide empire, it will help more than Liberty's mere 1 happiness per city.

All ideologies indeed add happiness, any city self founded that late won't amount to much. It's also though a great time to go conquering and attaching the empire, particularly after you've finished Hermitage, but you may want your conquests to remain puppets until you finish National Intelligence Agency for another spy (or diplomat). Following that you can pretty much annex everything after they come out of resistance.

Archers should be upgraded to Composites and then Crossbows quickly. They can stay at Crossbows for quite some time, but you evenually do want the to be Machine Guns. So time to upgrade to Gatling Guns is when Machine Guns are right around the corner.
Lancers should be upgraded to Anti tank quickly, but the Pike line really shouldn't be built at all unless your playing Poland.

The official "back stab" modifier is for AIs that DOW or Denounce you while you have an Active DOF with them. The other AIs will hate civs that back stab others so it's actually to your benefit.
All of them will do this is your relationship drops to Guarded or worse.

But you might have been referring to "pretend friendship", any AI that's showing friendly and no negative modifiers that a few turns ago was showing negative modifiers is doing this, especially if its your neighbor. It's kind of a joke how easy it is to tell that they are doing so.

A win is a win. But most Diplomatic victories aren't Science ones that went wrong, the initial intent was in fact Diplomatic. It's just that there is no difference between the ideal tech path between any of the victories (Diplomatic, Science, or Cultural) until very late in the Modern Era when you choose your first Atomic Era tech to research.
And actually, a Cultural victory takes about the same number of turns as a Diplomatic victory, both take fewer turns than Science.

12 cities? please, with order you can go 40+ cities

I have never know how to play wide, guess I'm too picky about city location and I mostly play on standard or small map.
The reason why you think tall is not good as wide is probably because your tall isn't tall enough. By the end of the game, if you are going tall, you should have 3 to 4 cities with like 30-ish or even 40-ish population. To growth this big, it involes almost always locking high food tiles and use caravan and cargo ship to send food.
I think the benefit of going tall are easier national wonders and centralized production. For national wonders I think joncnunn explained well, the only thing to add is that he missed out Oxford which is very powerful as well. And the benefit of having centralized production instead of scattered in many cities is you have a strong cap or city to compete for wonders. On immortal, I can pretty much every wonder I want except something crazy like Great Library. Plus, it would be faster and easier to get new buildings up in just 4 cities. I couldnt imagine how long would it take to get all the universities if I go wide. One more thing which I think is quite important is that the number of cities would increase the tech and policy cost, which might be a reason why you find science victory difficult.