Did I play well? General Game Comments Appreciated!
Well.
Since the second move of White, h3 I think he's not really a good player, however, on d4, it'll be better change the d pawn and trade queen, the position is open and you have got the couple of bishop, it has no sense complicated the position when the endgame is win for you.
4...h6 is your one serious mistake. 4...dxe4 gives Black an advantage, and you should know that for when your opponents try 1. e4 e5 2. Nf3 d6 3. d4 Bg4?
The reason 4...dxe4 is good is because White is forced to give up the dark-squared bishop for the knight. 5. dxe4 Qxd1+ 6. Kxd1 Nxe4 is just losing for White, so they would be forced to play 5. Bxf6 Qxf6 6. dxe4 Bc5, where Black is better because the dark-squared bishop is much superior to a knight in this position.