Expression Engine and PayPal and aMember?

Hi,

So here's my goal: to build a simple subscription-based site where different levels of subscribers can access different levels of site content. To be precise three levels of memberships. Whatever subscription he chooses, the subscriber's credit card should billed the same each month with the system.

The questions:
1. I want to use EE + aMember + PayPal to get the above done, is that easy?
2. What PayPal service *exactly* do I need to buy -- I need the billing to be recurring.
3. At any point during a transaction, will the customer have to go "somewhere else" to complete the payment?
4. How do subscribers *cancel* their subscriptions? Is it possible to set it up so that they'd have to call us first so we could ask why they are canceling?

Thank You,
Sam