White is unresolving the Nd4 situation, that is unstable, and this is a factor that has to be kept in mind for both players.

This is too early. If blacks knight is on f6 then first either f3 or h3 should be played.

I agree!

Good question. This should be considered a mistake. The "Moving two times the same piece in the opening" rule applyis here. I suspect white bet on f6 - Ba4, g5 - Bg3, to follow wih f4 and h3 to make very difficult black knignt's life. But the truth is that black can easily win the developement race with h6-g5-Bg7. But the threat black finds is much more creative. It has a little bug, though, due to white's ability to go Nd5 and threat the queen from there. This Nd5 will threat the known fork on c7, and this will prevent the BQ to lose sight of c7.

If white allows Ng4xBe3 and white takes back with the pawn, white's e pawns are doubled and isolated. E5 is weak and a great square for a black bishop or knight. Generally in open positions like this, the bishops are marginally better than the knight, which is why white avoids the exchange.

If black captures, white has an isolated and doubled pawns. Besides, white's black bishop is much more valuable than the black knight.

This move has the additional benefit to enable e5 for black. At this point, black has better 1) to consolidate with Be3 (again!), accept the exchange and the position is not so bad, or 2) accept to lose the d4 knight, and take revenge on Ng4, with h3. True is that black can go on Nxf2, Kxf2, NxN, but it is an alternative.

Here, white should have forseen the subsequent e5, the resulting pin, and his only escape route, Nd5. The bad bishop's managemen, joined with the interesting black's attack, had been white pay a lot. It would be interesting to know where both players became aware of Nd5.

A knight seems to be lost. White can't try h3 to compensate, since after exN the other knight is threatened.

It was the only way to get something back from the piece, a foreseen one.

Black is almost forced to cash in the knight. If Qa5+, b4 is ugly. Black threats Qxe4, so no more choice that exchange queens (and white can welcome it!)

So black has cashed the piece, but white stopped the mate threat and has his own resource still enabled: to win a delayed exchange.

More than the exchange (the assassin kinght will be taken sooner or later), white accomplished to paralyze black's pieces (lsb and R), where the other are no longer very acive. Whie got all the compensation he could for the piece

On games databases and theory books, of course.

This bishop's destiny is g3, no way. Black gets something back: more space and dsb's activation in support of the lone d5.

It's incredible how in this particular position the isolated and doubled black's pawns are not so weak as they may seem. Black has a ready made Be5 to reasset them, but he has also Re8, and if f3, Ne3. A third plan can be b6 and Bb7. IMO, the latter is not the best.