Nothing obvious in there, unfortunately. I would suggest contacting your hosting company at this point, to see if they can see what is being redirected there, if you are seeing redirects. It may well be something on the server setup side.
If you are only replacing files, then no. So effectively you are doing a merge, so it replaces any files which are in the upload
It should be noted, you should always take a full backup before doing anything of this manner in any case
This isn't really something new. This would indeed be what the contact form would be for. The same issue would apply regardless of us removing displayname login
Thank you for bringing this issue to our attention! I can confirm this should be further reviewed and I have logged an internal bug report for our development team to investigate and address as necessary, in a future maintenance release.
Any 'live' functions such as whos typing, whos viewing, live topics. Items such as courses that are added in our latest releases would not be released to older packages. Limitations on concurrent users were removed with the new packages also.
There isnt online user limits on any plans, no. Registration is the same no matter which you are on. You will of course not have any of the newer cloud based live features on the old plans
This would not be the recommended way of doing it, and to be honest has unnecessary steps. You could just as easily upload the files, add your conf_global.php file, and upgrade.
Thank you for bringing this issue to our attention! I can confirm this should be further reviewed and I have logged an internal bug report for our development team to investigate and address as necessary, in a future maintenance release.
I understand the thought process there, however of course we have to look at the product as a whole. There are many many things like this where people would like to see change or improvement. 1000 tiny things is unfortunately no longer a tiny thing.
Driver error is something from a very old unsupported release. You can check within cache/sql if I remember correct, which should show the exact error there.