64-Move Endgame Calculation Headache

I will preface this game by saying that I very recently broke into the 1000 rank (as can be seen by my rating) and I do not pretend to boast very much theoretical knowledge. This said, any advice on how I could have played my opening better would be greatly appreciated. I was proud of how far I got, honestly...

I spent a significant amount of time calculating my endgame moves, but I would love some feedback on where you guys think I could have done better.

4. pxp, pxp, 5. qxq kxq 6, eat the free pawn, woot

20. e5...what is reason for giving black a free pawn?

22.  qd3...giving away another pawn, your down two clean pawns now

23. d6...giving away yet another pawn, as black can play pxp check.  So you would be down 3 pawns, with no compensation

The diagnosis is clear, and 100% normal for a player of your level.  Tactical weakness.  There is not much point to talking "theoretical" stuff while your at this stage.  

Silman recently did a front page article here on chess.com covering beginner tactical weakness, so you could look at that.  I also recommend making a free account at chesstempo.com.  

Thanks a lot for the feedback. I sort of knew that my pawn sacrifices on the kingside were stupid, but I only realized that retrospectively. Additionally, thanks for the advice about chesstempo.com. I had actually never heard of it before, but I was frustrated that I could only get 5 free tactics a day on this site and now I do not have that problem anymore!