From the first diagram, I would certainly avoid exchanging all kingside pawns. Keeping even only one would be better.
Probably you messed up somewhere in the pawn pushing on the queenside, where you ended up with the a6 vs. a5/b4 structure - if you can push the b pawn supported by the a pawn to exchange, you will have passed pawns on the b and c file which should be easy to win.
Eventually, in the second diagram, I think White has still a good chance to win by relocating the king before pushing anything. Basically the black king cannot go too far from a8 or White just pushes, but if White manages to reach say e5 with his king the defense becomes harder - the black pieces don't have that much space to move, and there are always zugzwang tricks.
Playing online i came to this position with whites.
I was adventage, bishop against knight with a extra pawn in the queenside.
My plan was first advance the queenside's pawns to block the black king, then with the black's king busy, attack the kingside with my king looking for exchange all pawns or wining one. And if all goes well, then return the king to the queenside and try to promote one pawn.
All goes acording my plan and we reached the next diagram.
So here i made the mistake playing 55. b5+. After 55. ...axb5 56. cxb5 Kb7, all that blacks have to do is try to sacrifice the knight with the b pawn, and stay in a8. The game was draw.
My question is. Was my plan correct? or in the first diagram i hadn't to exchange all pawns in the kingside knowing that the bisshop is superior to the knight with disntant pawns ? or it was well and in the second diagram i had to try looking for move away the knight from the black king or try to catch the knight with my bishop & king ?.
Thanks.