Welcome Slush. Fair WARNING, this game can be habit forming (smile).
Most of your questions can be answered by checking the Getting Started and FAQs on the right of this screen. Not sure what you mean about "rewards", but you can earn credits that are used in the Pro Shop or to enter tournaments that are not free.
So you know, you'll need to play in rated stroke play rounds/tournaments in order to lower your scoring average. Closest To The Hole (CTTH) completions and practice rounds will not affect your average.
I am not aware of a sponsorship program but maybe someone else can respond to that.
Joey