There are several options. I would first recommend renting a cello before you buy to make sure it is the right instrument for you. There are many places who have rent to own options as well. In NYC try: ,
strings and other things , david gage, sam ash.
Places I think are handy for sheet music are: Patelson's
Yes! Several times a year all my students get together to work on some chamber music. I am a strong advocate ensemble work and encourage my students to join projects outside of lessons. Once a year I put on a recital for friends and family.
I give a free trial lesson where you can see my teaching technique. I focus on the technical, musical and spiritual aspects in a very relaxed, caring setting. Try a lesson there is no obligation! I also have many references please infer for more information.