I think the "Permanently asleep" thing is flavor text to explain its ability, which is that it can ONLY be affected by the sleep status (as opposed to Burn, Poison, etc.) That said, Wake-up Slap will probably function like it does on any Pokemon that's asleep if Komala has the status, but otherwise it's just gonna take normal damage from it. Well, super effective damage, since Komala is Normal and Wake-up Slap is a Fighting-type move. But you probably already knew that.
And yeah, I was actually toying with the idea of running an Electric Terrain doubles team with Komala on it, so that's a pretty good question. I assume it would? Not totally sure how it works in Gen 6, guess we'll just have to wait and see in Sun and Moon's case.