Questions in general about N Series phones

[Chips Have Salt]

I'm looking at the N80 right now but am open to other N series phones. Of course they can open standard web pages, but can they open more advanced things, like .pdf's or like a streaming .mp3 (cus Im pretty sure standard audio is old news)?

Also do the GPS systems in N series phones work well, for the most part? Almost all of my friends have newer samsung phones with "built in" GPSs". It only works on one of their phones, and not very well on that. My car is pretty old (ie. nothing of that sort) so having a just a very basic phone-based GPS would be helpful.

Also could I plug a car cassette adapter into any Nseries phones (so I can go hands-free)?