6fighters is the Norm. But i prefer 8fters, which is only during Harbor Assault/FleetWars.

6fts/2db

6fts/2 120 scouts

7fts/1 120 scout

8 fts

KM and US has the best fighters. I perfer KM over US.

KM fighters are slower and have less fuel than USN.
If you want to go for optimal fighters then go USN.
If you want very good DBs and fast fighters with most fuel fighters take IJN. 
If you want managable fighters and very good DBs take SN.
If you want to tear your hair out take RN.
If you can't decide take MN because they're all around good. 

i have km, very good, lvling us now better, had mn very nice will lvl another mn once us is done, always looking for a good cv to give me a fit so lvl them properly or i might eat though them.  Dont forget ur gunners and seamen.  seamen will boost the fps.  and no gunners and subs will drive u nuts.  i usally run 7 fps one scout, or 7fps  and seamen.

how about rm ft? is it good enough?

KM or US. 

6 fighters, 3 seaman
6 fighters, 1 seaman,  2 scouts
8 fighters, 1 seaman 

Pick your poison.

Bombers mean you lose FW status. Then it is a mixed CV

3 seaman is a waste.
Seaman don't stack linearly, but stack with diminishing returns. The influence of the 3rd is almost neglible ( about a 1% boost).