I have been playing the roy lopez for a while
Roy is okay, but Marth is better.
Yes, it is a d4 opening. It is pretty awesome, because your opponent sees d4 and thinks that it will be a quiet positional game. It's also quite "trappy" as you'll see in a minute. It is sound although it does have an "inferior" reputation in GM level (although it is played there). It had many similarities to the Blackmar-Diemer Gambit, but without the loss of the pawn.
Here are 2 quick games with the Veresov opening. It's quite scary how quickly a GM can lose in the first game.
I'm sort of new to chess strategy, can someone explain to me why black would not H6 on turn3? Seems like a good way to chase out the bishop.
3...h6 loses a tempo. The bishop can capture the knight and now black's kingside is pierced, while giving white the move again. It now becomes easy to attack black if he ever castles kingside: put the bishop on d3, castle queenside, shove the kingside pawns and checkmate. Now it's not as simple as that, but if you know your opponent wants to attack you, why force him to give you a weakness? Here's a little analysis and the first few moves of a game: