Hello Rashi,
Apologies for the late response, but I have been travelling and have just seen your post on the forum.
I have discussed your planned travel and living plans in Arusha with my Tanzanian friends who live in and around Arusha. Basically your plans are very unrealistic. Arusha is a tourist town and therefore is an expensive area to live in.
There are a few restaurants, and as a foody myself, I found the standard of food to be low unless you are paying very high prices. The only swimming pool that I am aware of is in a hotel and you pay to go each visit, so if you are going regularly you'll be paying alot.
Your $200 per month budget really won't go far, especially if it is for 2 people. With regards to finding work, you'll have to find out if your visa will allow you to work. There is a special 'Class C- Volunteers visa' that is also required for volunteering activities, but doesn't allow you to work. Finding work to cover your expenses will be very difficult since wages are very low and many people are unemployed so the job market is highly competative.
I'm sorry to be so negative, but I want you to go with realistic expectations.
Regards,
Sam