you have so many questions, it sounds like you have no actual experience with cb and joomla.

i suggest you start with reading this site.. installing joomla and cb.. and then reading many threads that explain different components that you might like to use..

from actually working with joomla you will build up a feel for it, it will make certain things obviously easy, and for other things you will use this site and joomla..

if you do not fancy diving in yourself, i suggest going to sites like rentacoder.com and explaining your wishes there. there are many ppl there that will bid to do your website. just pick the guy you like.