Writing to my host family

Next semester I am doing a semester abroad in Japan and will be doing a homestay while I'm there. I have to write a letter to my host family as a part of the application process, but I have no idea what to use to start or finish the letter. What openings are used in Japanese, like the equivalent of, "Dear Host Family." How are letters ended? I would like to say something along the lines of, "I look forward to hearing from you," or "Sincerely," but I never learned how to format Japanese letters.

Please do not worry about the "format" of the letter - you can start with "Dear Host Family" "Everyone at my host family" kind of phrase, and close with your name, after writing that you are looking forward to seeing them :)