Wordpress Multisite S2Member Setup

I have a Worpress Multisite installed and need to setup the Domains so that the S2member Membership plugin (or one you recommend that is multisite compatible and has the abilty to protect download content, but is also future compatible with Amazon. I have the following and would like to have the members have the ability to login (like SSO) on the main site and have access to all subsites. I have a master site, with multiple subsites: SuperAdmin [login to view URL] (BuddyPress/Forums and all accounts managed at this level) [login to view URL] [login to view URL] [login to view URL] I would like to have a common login (SSO) for these sites, so the user can browse the multiple sites without loggin into each of the subsites. The issues currently are many since I am new to all of this. I am currently trying to get around the issue of having to login (as the admin) to each site I open to administer. This I assume is happening for all users too. I am going to try to show the current content (from many of the sub-sites) on the [login to view URL], and those subsites will have the current content and tutorials on them for each of the software packages they represent. (an example of the sub-sites using MSOffice would be a site for each package of Word, Excel and PowerPoint.) So the topics on the sub-sites will cater to the usage of each package, but activity summarized on the main site.