Beale st runs from the financial district (Market end) to SOMA (Embarcadero end). Expect all dining around there to be pricy, but no more than other major world cities. The real cost in SF is housing. I like Mefil on Folsom for Indian food. Local Kitchen is also great. Go to the Truck Stop at 1st and Mission for three food trucks (vary daily) where you can get lunch for around $10. If you're looking to save money, don't plan on eating out every day. There are all kinds of bars and lounges around the area. There are monthly rates for bart and Muni; your lodging will determine which you need.

I don't know anything about laundry or cell plans. Good luck with your adventure. Make sure you go to some meetups! Don't let jaded locals color your experience :). Take the F up to fishermans wharf. Take a stroll on the embarcadero. Go to Chinatown, etc. These are touristy things but can be quite fun.