Closed Track testing

I want to get my latest release of the app out to an identified bunch of users quickly (about 1000 users). I understand that I can create a closed track. I must build a "Beta" apk and then
1. Upload a huge list of email addresses to it, and then send them all a linky
2. Wait for them to install and for them to give feedback on the new feature if any
3. after 2 weeks I want to build a release package, and smoke test it, then
4. I want then close the Closed Beta track , and have them all to be forced onto the new release instead of asking them to remove the beta, which is a little nutso, especially if that means about 500 people will have both apps, sometimes get confused, and will have to remember to uninstall. Will closing remove the Beta App? I know the app will have the banner thingy to remind them, but would like this to be neater. As a side note, I'm feeling uncomfortable having a list of 1000 email addresses, but that's off topic here.

I understand that changing the APP-ID also means customers cannot move their data between the beta app and the release or visa versa, that's a separate question entirely, and our preference in this case as it's an upgrade is to keep the app ID the same if possible. (Most all of data is in-cloud, so users would need to login again, so that complicates the experience slightly, which is a separate consideration.) I understand that this is not what Closed Betas are really for, but ...
Please tell me I'm misunderstanding the Closed Beta process itself (not the intent).