Increase how 'bouncy' the girls are by going to the settings and entering your age as 99.
Unlock Hair Styles:
To alter hair styles press White or Black when selecting characters.
Press X or BLACK while selecting a stage to alter the arena.
To unlock Hitomi, have a DOA 3 save on the Xbox and beat story mode on normal with Ein.
On any difficulty beat Story mode once with each character.
With Leon on Normal beat the Story mode to unlock Bayman.