Normally you just put the save where the savegames are stored (same folder as the roms or a saves folder depending on your setup) having the same name as the rom, just another extension normally .sav .
Some wear old clothes and look old, others think wear vintage clothes and look cool. I think the GBA is in the cool corner and guess where the ds phat is...
A photo of the pcb would help, then you know might found out which card you've got and which flashcard files you need.
Downloading roms is a google problem.
I buy there regularly: compare, check, check the size, check the price and don't buy SD-cards.
I saw people ordering a gun getting the picture of the gun (exactly as in the description if you read all the way down). I bought rp2040's, leds electronics...
You could revert to stock firmware and see if the problems are still present to eliminate the cfw being the source of all these troubles. But like all people above I don't think it's the cfw causing the problems. Good luck!
Lovely read!
I like the rng-nature hack though a positive should also have a negative. So like if you raise the critical hit %, you also raise the damage done when receiving a crit yourself. And when your chance of hitting is reduced the damage is increased. I recently got a (real) emerald...