Most of your questions are answered in the FAQ "About Payments."
Subscriptions are presently offered in VGHD and DB, not Classic cards. Any subscription will automatically renew and be re-billed at the end of the subscription period (1, 3, or 6 months), unless you cancel the subscription before it renews. It's easy to cancel and then re-subscribe any time you're ready, but re-subscriptions or renewals don't get you the 2 free cards -- that's a one-time offer (unless you subscribe for a new longer period -- they'll probably give you additional credits the first time you upgrade your subscription period). You can always buy and spend credits (or booster packs) any time whether you're currently subscribed or not.
I don't understand what you might be looking for as a "map."