The headband will set you intellect to 17 but never higher. I'd want my Inteellect to be maxed so better to go with 16 or 17 and get it to 20 via ASI and/or hag hair.
I think its perfectly valid to keep your Int at 16 and go for the good feats instead. Theres plenty to choose from, after all.
- Go Fighter 5+ (or Barb or Monk), pick up the extra attack and some class features, lose out on caster levels, get at most 4th level spells. Not ideal since you really want that 5th level slot for better Animate Dead summons.
This is incorrect.
He has to choose Fighter and he has to choose subclass Eldritch Knight.
Only an Eldritch Knight (6) / Necromancer (6) would still have access to level 4 spells. Any other Fighter, or Barbarian, or Monk, wont, since they dont get any spellcaster levels.
I also would like to add that only Fighter(6)/Necromancer(6) will give you 3 feats; otherwise you'll only get 2 feats (or ability score increases).
Personally I would probably go for College of Swords Bard (dualwielding + medium armor) and let the bard focus on support spells, while the Necromancer does the heavy lifting.