Annotated chess game

I seem to recall asking that same question somewhere! Since it was developed pretty much by Leningrad masters in the old Soviet Union it seems reasonable to retain that appellation. Those masters might take a different view, of course...

I'd call 1.d4 g6 and 2...f5 the "St. Petersburg" variation, because it starts with "modern" move order, 1...g6 .... "modern" + "Lenningrad" = "St. Petersburg" ... sorry, bad chess pun.

Yes, I think the main line in the Sicilian Dragon is still known as the Yugoslav attack

i would have played 4.c4 followed by Nc3 and e4.

Yes, 4. c4 is more common, and does score better on the computer databases.

I like 5.Bg5 here (actually I like Bg5 even earlier vs. the Dutch, 1.e4 f5 2.Bg5!?, but that's another story) intending Qd2 & h4, with an instant attack.

Also good here is 6.exf5 gxf5 (not 6...Bxf5? 7.Bxb7) 7.Bg5 - there's that recurring Bg5 theme again   and black's position is becoming very uncomfortable: black no longer has the option of ...Ne5 because of Qh5+.

As opposite to his brother, black's dsb, white's will be weaker. Of course it is not easy to see how can black open the diagonal, but c5 is still possible at some point.

Black is without a good developement plan. He must play with great effort into coordinate his pieces and get them out armoniously. Qa5-Na6-Nb4 could have been a try.

Prophylactic, too: Black was obviously preparing ...e5. Maybe he could have played it at move 7 or 8?

? Black might as well play 9...Ne4 here.

e6 was interesting. Black must go Nb6, and white goes Nf4 in order to protect the pawn. This knight can be kicked by g5, but this means to weaken black king's position... it is unclear (to me) to say for which player would this be good.

Gives white a nice space advantage. Maybe 10...Nb6 instead, intending ...Be6 and ...Nd5.