Using the databases is typical of correspondence play. I don't recommend it for imporvement., since in real play, you will certainly not have the databases to help, and you have to use your brain to recall/find the best moves in the opening.

I generally don't make much use of the database in-game unless I've never played the opening before. I usually only bring it out for annotations.

This move is acceptable in itself, but your real mistake was later, when you did not play ...d5, and let white to play Bg5. This would have caused serious problems, since your dark bishop is absent. Really, the "destroyed" pawns are not even a factor in the position. The control of the center and your ability to open it is the main idea.

h4?? this just looks real bad... how is white gonna castle now?

Pawn structure is by far the least important positional factor in a chess game. Rarely does a player get to use this advantage at all; it just looks ugly. For example, here you open up files on the kingside for the white use. Even in an endgame, white should hold the draw without signifigant problems with this structure.

Keeping the king in the center, Ke2 for example was far better. But white should have played 12.Rg1, with a big advantage.

I believe that white was already almost winning here and a few moves ago. After Bxf8, winning the material, white has d4 at a good point, ripping open the center, and making sure that knight on f4 isn't staying there for much time. It is a clever idea  , and can cause some practical problems to white.

We will see... I am not so sure this was the best move, although white should still be near winning after this. This gives white some more problems.

The knight on f4 will not be there very long; if white needs to, he can trade his bishop for the knight if it tries to support the f4. He can also break openg more lines for his rooks.

However, the point is that white does NOT need anymore knigside aggression, or any aggression at all really for now. He is up an exchange, a permanent advantage that will win the game in the endgame(after breaking a few more lines open for the rooks). Black is the one who should avoid exchanges, and ATTACK. Unfortunately, an attack with 2 pieces is not a good one.