List Segmenting & Cleaning

Hi, I have following questions prior to purchasing Mailpoet

List Segmenting
a) If the subscriber opt-ins to another list, can he be automatically unsubscribed from the first one?
b) Do you have a TAG or LIST based email system?

List Management
c) Your features says, clean your list by removing invalid emails with a FREE add-on. Will this be done at time of opt-in, before adding the dead addresses to my list?
d) Can I also clean the list based on the subscribers who don’t open emails.

Integration
d) I will be using Cartflows, JVZoo, Warriorplus or Clickbank as my cart, do you integrate with these platforms via API?