New 2005 x3 owner: Questions

[tw12lve]

So I just bought a used 2005 x3 and I had a few questions I couldn't seem to find answers to:

- Is the only place I can install a nav screen in that popup thing on the dash? I've seen pictures of it where the cd player is and somehow the climate control is moved down, is that just for newer models?
- I've read about this MKIV, but is that only for newer models? Is there a 2005 x3 specific nav system?
- If I wanted to buy it, where would I go for the best deal? I'm very tech savy and have no problem wiring it up myself, but is there even a place I can buy just the parts?
- If there's a specific x3 nav system, is it even any good? Does it integrate any of the cars controls, or is it basically like buying a 3rd party nav system?
- What are the parts involved for the nav system? A screen, a dvd drive, ...?
- My x3 has the satellite fin, which looking into it, the specs said it was pre-wired for sat radio. Would that help during the install or would I have to run a new wire to that antenna?

- Many of the things in the car are like my 2004 MINI. On my mini, I was able to make a custom cable and wire up my own aux cable. Does the 2005x3 headunit have the pins on the back for the aux?

- Is there a good place to buy parts for the car, or even addon parts that aren't made by bmw? I mention this as there's a guy in the UK who would make a bunch of different things for the MINI typically at much less cost and usually offered more features.

Thanks in advance