Membership Plugin with Protected Pages on a Sub Domain

Hi,

Can I use the Membership plugin to protect all of a sub domain, but sell the memberships on the primary domain?

So the marketing would be on mysite.com but protected membership content would be on members.mysite.com

Also, do I still need to install the shopping cart to sell the memberships, or is the Membership plugin + 2Checkout going to do it all?

Thanks,

Matt