can I rename an existing domain?

You can, but you should only do it if absolutely necessary.

https://technet.microsoft.com/en-us/library/cc738208(v=ws.10).aspx

Honestly, you'd be better backing up your data, taking notes on the structure and starting over from scratch.

There is a good chance you'll always have weird behavior in the future.

This isn't a simple machine rename, you are going in and changing AD.

Here is a step-by-step guide.

http://www.rebeladmin.com/2015/05/step-by-step-guide-to-rename-active-directory-domain-name/

I'd set up a lab and try it there first.

Also, before production, make sure you have backups of everything.

You might also want to get some more categories added.  VB Script is not where this should be.

I've requested that this question be deleted for the following reason:

no valid respopnse

I disagree that there has been no valid response. When the question is "Can such-and-such be done?" a response of "I'm afraid it can't, and here's an official statement supporting this" is perfectly valid.