5) It is not even possible to use /acs-admin/install as it bombs with an unrecognized maturity level, so you need to upgrade acs-admin and acs-kernel from using the APM manually before you can use the nice Install interface.
In general we need to support this upgrade path, the question is only of "how". And I have no clue, especially not dealing with 4).
A wise thing could be to offer an "Upgrade ACS Core" functionality in acs-admin/install. This would create a db backup, download all acs-core packages, reload all files and run the upgrade all in one go. Once done it would change the repository and restart. This should tackle 1), 2). As for 3) I think we should only offer releases using the Repository.
