Multisite shopping mall: best practices

Hello I was told that with Market Press you can use it on an unlimited number of sub-sites each with it's own ability to have paypal installed. Clients could then join as members with the membership plugin, or the sites could be added manually. All true?
And is Market Press specifically designed for multi-site in that it works better than another shopping cart? Would each subsite have the ability to change languages for the back end?

Finally,is there a recommended theme that would work nicely with a multisite shopping mall? Thanks!