Thanks for writing in and sorry to hear that, and thank you for remaining so positive
1) May I know what do you mean by "park"? You can uninstall it by deleting it (after activating a different theme). And yes, both parent and child theme. Yes, as long as you validate your product/license in your new site, you'll still get updates. And you can still download the updates in Themeforest.
2) You can do that by going into your license page here in Apex, then assign a new site in production and staging fields, then validate it in your new site's
Admin > X > Validation.
3) We could do that but that means we'll have to delete your current account (since it's a single license) and create new account for that license (with user preferred credentials). It's per request
4) No, you'll have to uninstall them manually one by one.
5) A better option for this is clean installation since you're deleting theme, plugins, and demos. Still, you can delete them manually in pages, posts, portfolio, slider, and more.