Lobsterboy:
exactly what it says on the tin . . practice counts for nothing, ranked goes towards your average and scored gives you level points . .
You are correct: Ranked rounds (strokeplay only) go to the average.
Pardon me for correcting you in further details:
Each single shot counts to the XPs (adding 1 immediately), and practice rounds count the same XPs as ranked / scored rounds.
Scored rounds (match/AS) go to the stats in a player's profile.
FWIW, some special stats (e.g. HIOs) are only filled in ranked strokeplay.