ICAO Annex 6 Part III (Operations) Sections 2 & 3 and any differences filed by Russia (see the annex) would be a good start.
JAR-OPS 3 was, last time I looked, an "orphan code". The JAA no longer exists and all the former national aviation authority members withdrew from the Cyprus Arrangements in 2009. All that is left of Pan-European regulation for commercial air transportation in helicopters are the individual national codes which, back in 2009, were based upon JAR-OPS 3. In the future the EASA Implementing Rules will take over in the EU and in the states on the fringes who have associated themselves with EASA, but that will probably be a couple of years in the future.
ICAO Annex 2 - Rules of the Air and the differences notified by Russia in the annex would be useful.
The Russian AIP may well have pages in English, but I'm guessing here.
A copy of the ICAO (Chicago) Convention would be handy.
If you are using a Russian registered helicopter you will need a Russian AOC for CAT and possibly a certificate for aerial work. If you are using another registration, then you will still need similar certificates, either way you will also need permission from the Russian government department of industry/aviation/transport to undertake commercial activity.
If you are planning to do Private GA then Annex 6 Part III Section 3 and compliance with the Rules of the Air and visas/permission from the Russian authorities may be sufficient.
D