Personal Edition does not include any of these features:
Transaction Logging (This allows you to view all PayPal transactions conveniently from within your ClassiPress admin dashboard as seen
here on the ClassiPress Admin demo)
PayPal IPN (PayPal's message service that sends a notification when a transaction is affected. You can read more on this
here.)
Sales & New Ads Chart Widget (This is the "Stats - Last 30 Days" Graph you see here on the right-hand side of the dashboard on the
ClassiPress Admin demo.)
Yes, you can easily upgrade your licence type at another time if you wish, via your AppThemes customer dashboard. You will only need to pay the difference between licence types.
All support is carried out via these forums, regardless of your licence type. We have an AppThemes support team, and also the community itself is very active, so often you'll find other customers may answer your threads as well. Support is not instantaneous, but we do endeavour to answer all questions within 48 hours, however it is often much sooner than this. We do not officially support customizations or third party plugins, so these kinds of questions would be subject to community based support.