What to get will depend on specifics. It's even money on whether it has 1 or 2 R gunner slots, but any BB crew should have 2 already, so it's a non-issue. For planes, I'd go with FP and maybe scouts, as it's just not practical to have a ship with even 60% of the Amagi's battery (assuming that's what it uses) and still focus your time and effort on bombing. Ise hybrid doesn't even have proper BB2 guns, so it makes some degree of sense to focus there, but this has no excuse. 
I'll note that it looks like there are only 5 T slots per side, so it may be prudent to use ASW instead. Giving it AA may be trying to do too many things anyway.

Regardless, I won't care since I already have full IJN BB6 and CV6 crews :P

What sort of support set ups would you use if it had 9 supports? I'm interested to see how many reps/engi/pilots, etc, people would consider using.

It's a good question isn't it.

I quite like the idea of this ship but at that level, id assume everyone has a full BB6 crew.

I'd probually use 5eng 2rep and 2 fp's instead of scout - possible HH instead of AA on board due to having the fp - I guess another option would be 6 eng 3 pilots and 2 reps on board but that has the downside of no hh or aa options so the 1st makes more sense to me.

Lots of options depending on plane space, I get the idea this is going to be a hard one to balance due to weight and different playstyles but could be a lot of fun to use.
Would this really be anyones Main Ship though?

Do you guys think new EBB/ECV will got repair cost as same as BB6?

I sincerely hope not.

I can't afford to play the bb6 i own as it is, due to saving for another. 

You'd ditch the scout altogether and not use any sort of bombers?

Well, at least it's cute.

Yea no bombers

id try to use fp's to scout / and protect myself and the guys nearby.
id less micro-manage the fighters ànd try play as a bb more

Of course thats depending on how the ship plays