Miguel,
As for your questions :
1/ There's no issue that I know of if you're "just" modifying units, but as theme modding isn't really possible you'll have to test it
!
2/ Changing the name (and everything else) of the site-specific unit works (I've done it), what's hardcoded is the link between site and unit #id
Now for balance I'm not at all a C'tis specialist, but I'd be interested in having a look at the mod
