Unlike their night elven brothers-in-arms, the blood elven demon hunters have only one true avenue to their becoming what they are: the Sunfury. What this means for the character is that they were part of the coalition of elves to follow Kael’thas Sunstrider away from Quel’thalas in the wake of the Sunwell’s destruction. These same elves were present (and survived) the attacks on Northrend by Illidan Stormrage, Kael’thas, and Lady Vashj as well as the conquering of Outland through shackling Magtheridon. The Sunfury elves who had either proven themselves capable enough, sworn vendetta against the Burning Legion, and remained loyal to the Illidari in the wake of Kael’thas’ betrayal would prove capable of becoming demon hunters in the footsteps of Varedis Felsoul, the first blood elven demon hunter.
2. Your DH needs supplies on a regular basis. They can only carry so much food, clean drink, medical potions and whatever else they want/need at a time. It's pretty realistic that they would need to visit a market every so often, and large faction markets will have the most variety and types of items to choose from. (My DH has been a recluse in the wild for some time, and she is stinky, dirty and has eaten some questionable stuff. This isn't really ideal and a Dalaran doughnut would be pretty flippin nice.)