Short answer, yes. All of those are very easy Modifiers. I made a reply in one of your other threads, you can use the processes I kind of detailed there to get it to work.
Long answer, yes, and I'll help you get started:
1) What effect do you know of increases XP gain by units by a percentage? Any building in the Encampment district, yeah? Open the base game's Buildings.xml, search for 'BARRACKS' or any of the other buildings until you get to either the Modifiers table, or the BuildingModifiers table, which should be below it. If you are in the BuildingModifiers table, then search for the Modifier associated with said building. That Modifier likely just attaches a Modifier to all units built in the city (of the right type maybe but ignore the requirements), so go to the ModifierArguments table to find the name of THAT modifier, then back to the Modifiers table. You should be able to find the modifier it uses, BUT that one likely only applies it to that one unit. So, open the Modifiers.xml file, and search for Modifiers with a similar name, or the same Effect but the Collection of something like COLLECTION_PLAYER_UNITS. Refer to the other thread from this point, probably.
OR, I just remembered Survey, a Policy which does a similar thing to what you want. Open Policies.xml, find its Modifiers entry, and you'll likely have the ModifierType you need! I just remembered after typing all that above, but sometimes you won't get so lucky!
2) Pretty much same as above. Discipline, first thing I found in Policies. Look it up in Policies.xml, and that's very likely the ModifierType you need. Or, maybe it's not! If the ModifierType specifically references Barbarians, then you're gonna have to dive into Modifiers.xml, find the ModifierType you're looking at, take its effect, and make a new DynamicModifier with the proper Collection.
3) I answered this in the other thread, even more thoroughly.
4) Yes, but this time what you really need to dive into are the Requirements tables! I forget where I got them, but I think somewhere on this forum someone got a list of every entry in all 4 Requirements tables, so that helps when looking up Requirements for me. Lucky for you, it sounds like you don't really need to do that! Here's what you do: open Civilizations.xml. Search for russia, find its entry in the CivilizationTraits table, there should be, what, 3? Ignore the ones for the Cossack and Lavra, and search again for the trait one. You'll find an entry in the TraitModifiers table, that will give you the Modifiers you need to look up (there will be at least 2!). For each, search them again, you'll find their entries in the Modifiers table, and you'll see the requirements associated with them. Search for those requirements, you'll find entries in the RequirementSetRequirements table, search for those and you'll find an entry in the Requirements and RequirementArguments tables for each of them. Almost there! Make copies of all of those tables in your mod, link them the same way, but with your own names for each thing (else it will cause a crash when you try to load it into the game). You should have at least one entry in the following tables: CivilizationTraits, TraitModifiers, Modifiers, ModifierArguments, RequirementSets, RequirementSetRequirements, Requirements, and RequirementArguments. In the RequirementArguments entries, you can just change what is likely TERRAIN_TUNDRA and/or TERRAIN_TUNDRA_HILLS to any other terrain type (and possibly hills). Make the appropriate number of copies of things you need for each of your effects, etc., and voila! Should work if you did it right.
There you go! I helped! If you want to post some code here when you've done some of that, I can look it over for you.
