Amaterasu is already falling out of the meta if Uriel is not an option Fire Amon would be best.Best choice this MT would probably be Amaterasu.
Important notes:
1. I refuse to use Uriel because of Waifu reasons.
2. Next MT Im probably picking up Vahagn, now having Amaterasu would mean Im more versatile.
No, Elemental attack>Character Attack get Andramalech instead1. Would it be worth to spend eidolon orbs to buff Ctugha?
Yes but you should get Tiamat(stat block) and a good primary eido(Andra,Amaru,Icarus) for every element for which you dont have one yet first.2. Should I save my eidolon orbs for Kaiser?