Is it really detrimental to the fight to have Galuf defeat Exdeath? Does the variant of Exdeath that Galuf fight offer any rewards like experience points or ability points to Galuf to transfer over to Cara?

I was not aware about either of the glitches that you mentioned. I think that ending the battle with Self-Destruct sounds like a fitting end providing that the dialogue between Galuf and Exdeath still takes place. Is there a video of this glitch somewhere?