I've lived near Exeter for years but don't study there. Here goes:
1.) Is Exeter really in the middle of nowhere?
-Well kind of, the South-West in general is a bit out of the way of everything. Exeter St. Davids station has 2 routes to London, one for Ldn Paddington and Ldn Waterloo. Regular trains to Bristol, Plymouth and Cornwall, services to the North (Manchester) and then local lines around Devon. There is enough to keep you occupied here. Crime rate is low, nice sights, decent nightlife.
2.) Is it more of a sciencey kind of school (as I've been told also)?
It has all sorts of departments. Exeter is starting to become a science hub but it is in the top 10 or 15 in the country overall so I wouldn't worry too much.
3.) Is there much of a music scene?
Yep, and you'll more than likely adore it. Lemon Grove (SU bar), The Cavern, Phoenix and Mama Stones all have live music and club nights. Nightclubs are Timepiece, Arena, EX4, Mosaic and a few others that escape me right now. Nifty guitar shops around, if you know or like Muse, they have their guitars made at Mansons Guitar Shop in the city centre.
Hope that's helpful.