Bug found and fixed. See https://github.com/i-MSCP/imsc…b6f2d5312ebf78fafe33365a5
You can now rerun the i-MSCP installer.
I've also fixed the PHP problem by disabling apc module and purging related package.
For any other problem, please create a new thread.
Thank you - I'm sorry, that it was so an "big" work - but I know, some (many) things are amiss, and the machine is "a little weak on the chest" but is runs as long as it is not turned off 
I'll check if imscp is now installable and if other problems occur, I'll come back.
Thank you and a good evening....
hempelr