the main site of Irina seems comprehensive: https://russiable.com/
- of course it's possible
- from West-Europe, after EU closed flight to Russia, I have just used flights to nearest border crossings then minibus, bus, car:
Storskog after Kirkenes in Norway.. Planes from Oslo arrive around 12:00, minibusses to Murmansk wait outside arrivals, to the right. For instance Borodin minibusses: https://borodinbus.com/transit
Gdansk,, Poland: from airport train to downtown main railway station (glowny), busses to Kaliningrad depart from old PKS bus yard, on the other side of the boulevard. From Kaliningrad several daily flights to SPb.
Narva and Luhamaa crossings in Estonia, respectively to SPb and to Pskov, busses from Tallinn.
Riga, Latvia, there's a route with Ecolines to Pskov
some Telegram channels list people doing the rides with their cars and taking passengers for a fee. In russian.
- yes very easy to travel in Russia, extensive transportation means.
Practically it's good to:
- get a SIM the day of arrival, at MTS or Megafon or Beeline shop
- a MIR card ie open a bank account. You bring a bunch of cash in € or $, go to Sberbank, exchange to RUB, and deposit on your MIR car. Install the bank app on the phone.