Hi @onealfa,
regarding point 1, yes 90% is the maximum value for VP, it's implemented like this and I don't think it's a big deal if it's 90% or 95 %, this is not a bug - it's just implemented that way.
Point 2 indeed is a problem. It is possible that your voting power drops a bitbelow your targeted percentage but 20% below your target is definitely not the expected bahavior. Until now, I couldn't reproduce this behavior with my personal account, thus I need to do further investigations.
Regarding your improvement suggestions I think you made some really important points there and I'm, willing to implement these changes on the platform. Nevertheless it will take some time, as I'm the only developer at steemvotes, and of course it's not my main occupation (and as you see above there is a lot of other stuff to do).
Sadly I don't have discord but you can contact me at steem.chat (georgontech).
Thank you very much for your detailed reply @georgontech