I think you may have more success if you tried asking more focused questions and giving more background information.

My suggestion? Read the wiki. Read the posts. Figure out what your current interface can do and what it can't do. Try downloading some addons. See what works for your play style.

Some people like clean interfaces, others like lots and lots of data on screen. Some people like to use the same interface for all their toons, others use different tools for their main and their slaves.The real answer here -- as mentioned above -- is personal preference.

Did I mention read the wiki? There is enough information there to help you make some informed choices about how to get set up. Ultimately, though, those choices are up to you.