My first BMW!

Hi I've just bought an N reg BMW 525 tds. It's my first BMW and I am well impressed.

I've been looking on the net for more info about my car and hence I came across this site.

There's a lot of detailed info which is a bit daunting for a newbie like myself.

I have a question I hope someone could help me with it, how do I know if my car is a E34 (?) or E39 and what does that mean?

Also mine has old style headlights where the headlamps sit separately to each other, is there any way of getting newer style headlamps onto it?

Thanks in advance for your help.