Can a sign up to my 3rd party list (i.e. Aweber) be counted as a 'sign up' in the affiliat

I'm having my affiliates send people to our sign up page for a free event. I want to count a 'sign up' in the affiliate report for every person that signs up through my Aweber form, not with our WP site. Is this possible with the Affiliate plugin?

There will eventually be a paid product that I also want to be able to connect back to my affiliates through this freebie referral. Does the paid product have to be via the membership plugin (i.e. they purchase by signing up through the WP user interface), or can it work with a simple paypal buy now button?

I guess I'm unclear how the affiliate plugin tracks the purchase...