Hi,

After 1.e4 c6 2.d4 d5 3.ed cd 4.c4 Nf6 5.Nc3 I like to play 5..e6 as black, since it can transpose to a Nimzo-Indian, which I also play as black and because the types of positions appeal to me, but my only Caro book, Houska's Play the Caro-Kann, doesn't cover 5...e6. Now 6.Nf3 Bb4 is typical, but after 7.Bg5, I'm not sure how to evaluate the following approaches by GM's playing the black side (is one choice considered better than the others?):

7...Nc6 transposes to 5...Nc6 lines (which I am trying to avoid since I play the 5...e6 lines) but with the black's dark squared bishop on b4 instead of e7.

7...Qa5 8.Bd2 Gulko-Smyslov 1976 seems to lead to forcing, independent lines. This game was later drawn, but other games between strong players in this position have often been decisive.

7...h6 can lead to several branches. 8.Bf6 Qf6 was eventually 0-1, Ivanchuk-Dreev 1993 (this line is given = by NCO after a few more moves from the game continuation),  and is rare but 8.Bh4 00 9.Rc1 Nc6 was eventually 1-0 in I.Ivanov-Seirawan, 1988. I wonder why Seirawan didn't play 8...Qa5, since it seems to take advantage of the move order not available after 7...Qa5 8.Bd2 (the bishop can't get back to d2 after 8.Bh4) but perhaps after 8.Bh4 caslting for black is no worse than 8...Qa5.

7...00, was Dreev's choice in a game played after his victory over Ivanchuk using 7...h6, perhaps to avoid weakening his castled position, or simply to save a tempo (sort of), or did Dreev just have a particular transposition in mind, since 7...00 seems to offer many opportunities to transpose to more established Nimzo-Indian and Caro-Kann theory?

Of related interest is if white tries 6.Bg5 (a move earlier than 7.Bg5). Then 6...Be7 7.Nf3 Nc6  can transpose to 5...Nc6 6.Bg5 e6 7.Nf3 Be7 lines but does black have other playable options besides transposing with 7...Nc6? I might try to meet 6.Bg5 with 6...Bb4 once I understand these transpositional possibilities and the resulting positions better.
 
Thanks