Well I was thinking that when you die. you go to a check in station and you are to go to which ever 4 kais you see for example
if you die on earth- you go to King Kai
if you die on Vegeta- You go to South Kai
if you die on Namek- you go to east Kai
and if you die on Konets- you go west kai
and the Kai's should have elemental attacks that can only be obtine by them by paying your BPs
So basicly that for the 4 regualer kais.
now the Superme Kais they give you good Trainning spots and give you good amount of training
Now Grand Kai and Grand Superme Kai These guys are to place they should give like a transformation Mystic. Like how Grand spureme Kai did to Gohan. But it would be only for half saiyans.
and for the God Kai is the only one that will give you good amount of customized attacks if you do some quest and your power level is at a certain point. For example
If you want a super finsher Customized attack than you have to complete all the quest of Heaven. If you want Combos Customized attacks Than you have to complete half. and so on and so forth.
That what I think