This way you will have most of your needs met. You wanted travel tips. I've stayed in Dorndorf twice, and the main obstacle is food, especially if you're a vegetarian. Try to find a place that serves meals. I also understand that if you call the house, they'll know.
Phones are the other problem.
Two alternatives I know of are to rent one before you leave, or get an access number in Germany for your carrier. Otherwise it's really lovely, especially walking back after darshan when there's a fog.