I lived with an American friend as well as people from other countries through my school life. And yes, it is different then how you interact with them in public.My intention was similar to yours, to experience American life closely and I am very glad I did and today we are very close friends and also with his family so go ahead.
Many working or educated Americans are clean and are very independent. So good luck with eating their food even when you walk into your apartment starving unless you have become very good friends. I learnt a lot of things from him and became more independent myself and learnt how to fix my own car, learnt to have shower curtain spread after you take shower(if you dont the water is trapped and you will get mold and get sick), I learnt more about hiking, places that Nepalese never go to, eat new food and meet more people and also networking. Its been more than 9 years now and I don't regret a bit and am proud to have an America reliable friend than some shady Nepali friend who is always talking behind your back but acts like bff when in front of you. And trust me, on top your English speaking improves a lot and it helped me a lot to understand American slangs, jokes, reply to sarcastic jokes at office. Trust me and utilize your time while you are young and don't hesitate to learn about other cultures, there are good and bad in any culture so learning the good side wont hurt you. PS: Shower Everyday and put moisturizers. Smelly people, hair with dandruff and cracked skin is a big turnoff if you are thinking to hangout with some educated and working Americans.