I remember someone telling me but i can never remember if its coins that are a third of your gigas won and gp a third of your xp won or something like that? :)
Pretty sure gp is half of the base exp, without the added multipliers like tier 3 or membership. I don't know this for a fact, though. I think 2x and 3x on weekends DOES effect exp. Could someone clarify?
GP is half of the base exp. Like said above.
I believe coins are half the exp.