Can the plate be cleaned with IPA 80%+?
Yes, I clean all the plates with 99,9% IPA before every print, never had issues
Agreed. I usually use a simple soap and water mixture or simplegreen then finish off with an ipa wipe.
What about textured plates? Also IPA cleanable?
Yeah, you can use alcohol on any buildplate
Just don’t use acetone 
How about Windex? I exclusively cleaned my Prusa bed with it and worked great.
I don’t know about windex, but many people use detergents, soap and water to clean it.