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.

There are other options outside of NYC which many of my students use as well:  robertson violins, usa band instruments

  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.