Hmm, Saki looked like she aged a little. That means:

1) It was just her dress (I don't think so)
2) They age until their mid-20s
3) They age indefinitely, just slowly
4) She had her curse removed after some time.

I'm going with either 2 or 3.

As for the purple unit, I hope that the weapon allows her to tap her mind into the machine (ie it sets up an interface between it and her mind even though there is none), instead of just being an auto-hack weapon. I doubt that's the case but it would be much better if it was because then it'd need actual skill. On the other hand, none of the other pilots got their "skill" from any prior knowledge (though I think Haruto benefits from L-Elf's marksmanship when he uses his body to pilot instead).

The heat transfer idea shouldn't have worked based on how little surface area there is. It should have been some sort of form-fitting equipment (like a net) instead of an iron. Oh well.