do you want the solution/source of the link sc3demo.nestar.se?
or the new templates for relateplus - which are not yet finished for relase?
Either way its best to contact one of episerver partners managers and they can arrange something.
About if second db - so no. EPiServer CMS and community share the same database for Relate+.
About User profiles - Episerver Community is using .net 2.0 membership provider for authentication. In documents section and developers guide - look at the first tutorial about user management for some examples. In Relate+ demo templates we tried to minimize the use of episerver community security handling due to major refactoring of thoose classes as of now. E.g. They are moving to a new namespace episerver.common - to be shared between cms and community core. But that is not finish for release yet.
But you will see many news in Episver Community namespaces and functionallity in near future when they get ready for relase.
hope this helps/clarifies.