Isopropyl is certainly compatible with Tamiya acrylics, but it isn't great for thinning or cleanup. Isopropyl thins flat colors just fine, but it's poor for use with gloss colors. For thinning, use the Tamiya's own thinner. Yeah, it's more expensive, but if you're only using it for thinning the 'added expense' is trivial.
On the other hand, while isopropyl is terrific for disolving Tamiya acrylics, it really evaporates much to quickly to be a good cleaner. There are much better 'bargan' choices. My two favorites are Windex glass cleaner and Simple Green cleaner/degreaser.
FOr clearcoating, use Tamiya's own acrylic clearcoat (X22, I think?), thinned with Tamya thinner. Do yourself a favor and get the thinner in a 'large vat'- it's cheaper that way.
Tamiya clear is inherently compatable with Tamiya acrylics, is completely safe over decals, and is
FAR superior to 'substitutions' like Future.