1) powerstore is not installed in extension manager it is a completed web site.
2) You can;t "upgrade" because literally every page has changed in some way.
Thank you for the suggestions on improvements (where were you a month ago when we were working on version 2). We will continue to work to add features. Unfortunatly because this is a web site and has no user interfaces it will always require replacing all of your pages and will be like purchasing a whole new store.