Wo, wo, wo, there! This could take a while.
Go here:
http://www.sba.muohio.edu/benamajh/old%20classes/385artf98/cablemod.html
This link will answer a lot of basic questions about cable modems in general, but it won't address some of your noise questions. Read through this and come back with questions after you're done.
P.S. I know exactly how you feel! We've all been there.