Minimum commitment when volunteering at Norwalk, Stamford or Greenwich Hospitals

Does anyone know what is the shortest period for which you commit to volunteer at Norwalk, Stamford and Greenwich hospitals? And how strictly do they enforce that?

I know that Norwalk hospital wants you for at least 3 hours/week, at least 6 months, but what about the other ones?

I would like to volunteer at one of these hospitals, but I am also starting nursing school in six months, and would like to continue working as a CNA to be able to pay for school. I am just not sure that I will afford it to volunteer then, though I would gladly do it now.

Also, if you get hired at a hospital, will they keep you both as an employee and a volunteer? Does anyone there have a similar experience?