Help With These Russian/Former Soviet Republic Stamps

Ok I'm trying to finish documenting both of my Middle Eastern/Central Asian and African collections finally but somehow more stuff keeps appearing. Anyway, I have been sorting and found these. I can read a bit of Russian (Basic anyway) and so far, I've been unsuccessful at finding these. I hope you all could help.

1) First of course is Azerbaijan, but which one is it or is it a fake?





2) This I don't understand. Maybe because its old russian instead of the modern russian used today.



3) This is modern Russian I know, but what area? And do these exist as some sort of stamps pre-printed on envelopes or are they not perforated?





4) This however is not in a language I'm familar with. I was thinking Armenian, but I'm not sure.



Thanks a bunch helpfun people!

The two stamps in #3 were issued by the Far Eastern Republic (and they are stamps not cut-outs).

The stamp in #2 was issued by the Priamur and Maritime Provinces government after a revolt against the FER by White Guards. However, the stamp was originally prepared for use by the the Far Eastern Republic and says "Dalni Vostochnaya Respublika", i.e. Far Eastern Republic.

The 2 semipostals shown in #1 are semipostals issued in 1922. #B1 and #B2 in the Scott catalog. I'm afraid I don't remember how to distinguish the genuine from the counterfeits. Real and counterfeits are both common.

#4 is Armenian 1922 SC#300