The Gigabyte UP5-TH has two Thunderbolt ports, that seem to be fully supported, though they are not hot-plugable and the TB device needs to be plugged in before a startup.
Yes, there are, but mostly Hackintoshs seem to work well. I also have one using the UD3-H board and the only hiccups I experience are USB 3.0 ones.
The rest seems to work fine.