Hmm, a list of basic questions. Smells like homework to me. We will not help directly with those. You learn more by doing your own research.
In any case, we don't have much respect for laziness around here. Most of the answers can likely be found with a few web searches.
If after doing some legwork you still need any help understanding what you've found, then you can come back and we'll help you with any specific questions you may have.