Isn’t this already the case in vanilla? Vanilla fe6 (and fe7 and fe8) gives 1 exp on a whiff, and I assume that exp from a chip or kill can’t go below that, although I’m too lazy to go test that right now.
No, the 1xp on a whiff is only if you attack and miss or get attacked and miss or can’t counter.
You can get 0xp for kill and chip at a difference of 29 levels or more (so you usually don’t see it), or if you mess with the patches.