[Sundraoi]

1. There is a thread you can check out for all the information of the gods of Faerun here http://thaypw.org/showthread.php?tid=22.
2. The nationality is Mulan, the language and pantheon are Mulhorandi.
3. Not necessarily. Mulan are the upper class of Thay but they don't all stick to their Mulhorandi gods. You should be fine sticking with Helm.