Tint

Hi, I just bought a 2008 Audi A6. First time getting an Audi. After contacting Audi's customer service email, they told me I did not have a Nav unit installed. I have seen some threads here about installing one yourself. I was wondering what will I need specifically to do this installation, or would it be better to use a cheap Garmin one. If you have done this installation, would you mind sharing how you did it and what issues I might encounter? How good is the nav and how much is it to update it? I believe mine is 2G but I've read you could upgrade it to 3G or 3G+. Not sure how feasible that is.
Also do the A6s come with an AUX port? The dealership I talked to believed there should be a wire, but they think it might have gotten pushed into the top of the glove box. I have yet to find it besides one installed by a third party that doesn't work. Would it be possible to play Spotify over Bluetooth or is that only mp3 platforms like iTunes?
Thanks!