Affiliate Plug-in Questions

Hi. I have some questions regarding the Affiliate Plug-in.

So here goes :
1) What are the 1 month, 3 months and 12 months payment options under Supporter payments settings?

2) I charge $2 per month for Supporter and would like to pay $0.50 per signups per month. Isn't this possible? What could be the solution?

3) How can I choose to pay only annually and disable monthly payment option?