What exactly do camshafts do I think I have an idea just want to see how you guys put it.

And if I get Hot Cams do I need to jet it still if I get an intake and exhaust system?

 

Cam shafts have one job in life; they open the valves in the engine. That is all they do. Nothing more, nothing less.
As far a the jetting goes if you flow more air through the engine, your going to need to flow more fuel to keep the ratio correct. So yes, your more than likey going to rejet.