Not the right season as it will be snow every where and roads will be close .if you are just going for relaxation and enjoying chill weather then it's ok
All place in a same route, i also travel all the placed you mention in your question all there place are look like heaven on earth specially the environment of the dharamsala and dalhousie is very peaceful i think but the month of January too cold. i traveled in the month of April that is fine. So i suggest you travel thesa places.
But if you are completely vegetarian than you have to suffer food problem. Thank You:
Darik Elwan