Pro site - Something i don't understand

Hi, i'm testing pro site 3.0 RC, and there are some things i don't understand.
When a user uprade his site, how can he cancel his subscription ? Only by going to paypal site and cancel recurring payment ?
And how a user can know how many time left before his pro statut expire ?
And about upgrades, what is the process ? User have to wait untill his first subscription finish to suscribe to a better one ? Or he will pay 2 subscriptions ?