Thanks for your detailed feedback, interesting stuff. I liked that Re1+ intermezzo you mentioned. If black blocks with the dark-square bishop, white can eventually force him to lose castling rights anyway, so I think better is to block with the light-square bishop, but in either variation, white snatches up the d4 pawn with the queen and then the b7 pawn with the bishop. That gains white a tempo as you mentioned, and after black slides over the rook, white can then move the light-square bishop to attack black's queen (because it's defended by the centrally placed queen. That gains white another tempo, and then he can snatch up the a7 pawn with the queen. It seems like white would win both of those variations. Looks like I was a bit too reckless there!
Counterattacking Slow Development

Very nice. I like chasing white's light-square bishop in the Ruy but now I will have to think twice! Even if he hadn't gotten his queen forked I liked how you got the material back with the bishop pin. That's the kind of stuff I fall for!
14...Bxh3 fails to the pretty obvious 15.gxh3 when black has some compensation for the piece but it's just not enough to checkmate white.

That's a good point Ruben. The more I look at this, the more it's clear that the sac was done without enough support. No good in most variations.
Out of curiosity, what would your plan of attack be at move 5 to exploit white's slow development? I'm interested.
I'm a beginner, but I guess a good way to punish slow development is to castle quickly, open the middle by exchanging d and e pawns and place the rook on the ennemy king file.

Marshall once opened a game with 14 pawn moves (chasing knights) and crushed his opponent with the extra space it created. However, usually "needless" pawn moves mean that your pieces are not developed, and your opponents are developed. It's all about who has the most force in the short term in the scene of action. If pawn moves create space and pressure, they are good. If they attack something that is less important or are wasted, then take advantage by creating your own opportunities by developing your pieces (or better pawn moves, I suppose - but generally pieces since they move faster and therefore create tactics in your advantage).

I would play 5. ...Nxd5, put my bishop on c5, get castled and go for typical plans like attacking f2, Qh4 and pushing e4 in an opportune moment like in the philidor. If white plays c4 the d4 square is now extremely weak and Bc5 after something like Nb6 gives black a very nice positional advantage where white is potentially already lost

White is essentially lost after he refused to take the bishop on h3 because after Qg6 he can never play Kh1 to take the bishop because h3 will be weak as well the b8-h2 diagonal. I would have also played 17....Qh5 and hope white takes the bishop and I get to follow up with Rad8, Qe3 defending the bishop and h3, Rfe8, Qf3 trying to trade queens, Qh4 attacking bishop, although I can't quite figure out what to do after Bd3. Maybe some insane attack like g5,Rd5 and g4. but thats just me

Here's a common problem that many beginners don't understand. They think that pushing a3, a6, h3, and h6 just resolves all problems as the b4, b5, g4, and g5 squares are often common posts for minor pieces as the Bishop can get there in 1 move and the Knight in 2, unlike squares such as say, d3, e3, d6, and e6, where these are not as frequently homes for Knights as they take a minimum of 3 moves to get there, and you are only on the third rank at that point.
That said, the major problem with a3 or h3, especially if d4 and e4 are played, is that they severely weaken other squares on the board.
If d4 is pushed, and you play a3, you have just SEVERELY weakened the c4 square, and the c4 square screams "OUTPOST FOR A BLACK KNIGHT".
Same thing can be said about f4 with both e4 and h3 pushed, or c5 for a White Knight with a6 and d5 pushed, or f5 for a White Knight with h6 and e5 pushed.
Only make these pawn moves if necessary. If your opponent does such a thing, look for those 4 outposts to post a Knight in. The reason is that it's hard to push the Knight away as if Black pawns are on e5, f7, g7, and h6 with a White Knight on f5, pushing g6 will often cause the h6-pawn to just hang. If it doesn't hang, the structure is severely weakened at least.
I played a game recently where my opponent, as white, played 1. e4, 2. d3. 3. a3, 4. h3 (total of four consecutive pawn moves to open). And I've seen quite a few people play both a3 and h3 at some point in their opening moves (or a6 and h6 as black).
I'm low rated so I'm still figuring out how to take advantage of extra tempos when I have them, but I'm thinking that I should be able to take advantage of the slow development. In this game, I tried to get an early mating attack going. I'm not sure how sound it was, and my opponent gave up his queen anyway, but my general question is how would you have proceeded against white's opening here starting from move 5? I'd like to be able to take advantage of those pawn moves more in the future. Here is the game with some annotations of my beginner thinking!