About 8000 yen including lunch and service charge at lunch

Free to go as you like(just not naked)

Yes you can, visit their website to get more infos. Also you can visit https://www.instagram.com/stefoodie.yt to get an idea of the food they serve

In my 3 times there, they did not have any other options besides beef dishes. So, safe to say no.

beef only

You should email them. They are pretty responsive via email

Of cos