The f5 Opening

5.gxh7 e4 6.Be2 Rxh7 and Black has sacrificed a measily two pawns for massive kingside attack. Looks pretty desicive for black, you are right I suppose, in that black is clearly doing great.

Yereslov Here is a better opening: 1. e4 f5 2. exf5 c5
I never fail to be impressed with the opening expertise displayed by players rated <1300 who want to share their amazing insights with the rest of us.
BUT, I will agree that the "Yerselov Opening" is undoubtedly "better" than being diagnosed with a terminal illness or getting run over by a Mack truck

It was a joke. Anyways, I'm not rated 1300+. I'm rated much higher.
SORRY, I tend to take things too seriously on occasion... unfortunately, there are lots of other members posting stuff like you did who seem to be deadly serious about it - unless they're all fooling me, admittedly not such a hard thing to do a lot of the time

I recently played a game that started e4 f5 and I declined the gambit. A bad mistake. I could have got better out of the opening, but me and my opponent got pretty equal. I eventually managed to win since he missed some tactics, which ended me being a knight up.

No because you forgot d5
Dude stop playing f3 for white. You may have an obsession with pushing the f pawn, but I don't share your enthusiasm.
This is an immediate 1-move refutation to your 5. d5.

My chess teacher used to play 1.e4 f5 2.exf5 Kf7! (sarcasm) in blitz games sometimes. He called it the "Porkchop." The games would usually go 3.Qh5+ g6 4.fxg6+ Kg7 5.gxh7 Rxh7 6.Qg5+ Kh8 or something like that. Obviously black does not have compensation for two pawns, but it's the kind of position black has chances in, and it was certainly easy for him to outplay weaker opponents.
1. e4 f5 2. exf5 g6 3. fxg6 Nf6 4. Bd3??
Bd3 is a loss for white. I will show you why
So tell me when did black get to play e5 as an extra move?
If its white to play in that position, white has a pleathera of winning moves.
If its black to move, the position is like a poster on my school wall: its always held by sticky-tack, it will eventually fall down later that hour.