You can watch the incar from youtube if desired. They're not in a "class" but they're based around similar specs as the GTE cars. (basically a bragging rights deal)
Apparently the garage stop was just to inspect the car for any debris damage, after being behind a crash. Went to watch nascar and haven't been keeping up, but during the qualifying broadcast they showed a tweet from HMS saying they were running the leading GTE cars back down. I guess Jimmie Johnson was behind the wheel. (I expect him to crash the thing, but we'll see) lol