new homeowner with banging and painting

kyle turner

I'm a new homeowner with two questions:
1. The hotwater system with old radiators bang. I've bled all the radiators, but only the 1st floor ones release water and the 2nd floor never release water. I bleed the 2nd floor everyday and they only release air. My elementary understanding is that there is not enough pressure and/or water in the system. What do I do? Simply add water to the system?
Also, I plan to paint a room, but after I've closed the supply valve to that particular radiator, water stills comes out when I try to disconnect the radiator. Has the valve failed or does the valve only reduce flow not stop?
How can I remove it, do I have to shut off the boiler alltogether?
Thanks