I'm sorry about the delay in responding to this. We're getting used to our new forums and site and apparently have missed setting up some necessary alerts.
As to your questions:
* When you install JStats, we only enable the Users stat by default. You need to add whatever other stats you want to display.. which it sounds like you tried, but....
* The "Class J2Store Not Found" error is curious. Can you let us know what version of J2Store you have installed on your site? We've been testing mainly with 3.3.x
* Additionally, can you check that the "System - J2Store" plugin is enabled? That's required for most J2Store functionality, so we assume it's enabled. However, we probably should add a check to make sure and prevent any problems.
As for the jQuery issue, JStats assumes that your admin template loads jQuery. Are you using the standard Joomla admin template, or something else? We can also add some checks for this, but would love to hear about your setup first.
Thanks!
Alex