Greetings - Should I purchase the Standard Version and decide after that I want to upgrade to the Professional Version is there any difference other than the link back? Would an upgrade like that require any interruption in the existing Standard Version, require any reinstalls or changes that would be affected with updates to either Joomla or JomSocial?
One more question, most likely dumb - will JomSocial integrate with any Joomla template that I decide to use?
No it wont, you only do upgrading like as usual, it wont effect too much on your old standard edition, except you have some hack from core Jomsocial code, you should backup it first.
Yes, it will work with most of Joomla forum. But if you have some conflict with Joomla template just let us know.