mobile

Hello everyone I'm new here I just recently rooted my Galaxy S4 i9500 and I want to put in cool speedy Rom.
I also heared that I can combine it with lolipop or something? I dont realy understand it yet I hope you can explain it to me help me choose what's best for me without bricking my phone....
Also I would like to know what apps I must have after rooting or what apps you recommand for me?

Any help will be aprreciate thanks for all !