1. It doesn't matter, as the SQL with Electrical is an express version it will install it's own instance.
2. EPDM has an OEM version of SQL 2008 R2, I think it's SQL standard. You are only allowed to use it for EPDM databases.
3. Yes, but that will probably limit the memory usage of the database too much for EPDM.
4. No, the license does not allow that.
thank you very much