She kisse dyou because she owed you. its not a sign of interest in this case i dont think, especailly if she says it doesnt mean anything. I think its a weird move asking her to kiss you, oh well.
Getting out the friends zone is all kino, and cocky funny suggestion. after the favour you could of said, "so when do i get my shag?"(joke ofcourse

) or some thing along those lines. Its also about showing a new you.
as far as after a kiss goes, im shit at it and would love some responce on good things to say/do after a first kiss.
I usually come up with some crap like "yum" ergh