I sense that you have a larger question that these small ones are coming from. In particular, I don't think most of those words mean what you think they mean. What are you trying to figure out, at a high level?
Edit: Eh, I'll answer. SE Linux protects against programs doing unexpected things, like apache suddenly accessing files that aren't explicitly marked to be served as web content. iptables is the Linux kernel's firewall, and chains part of the grammar that expresses its rules. It's responsible for limiting what traffic goes into/out of a machine, as you can't, for example, exploit ssh if it's impossible to make an ssh connection in the first place.
Last edited by karamarisan; 08-05-2009 at 05:35 PM.