ive answered all of your questions except the numbers 7-8 (which i know nothing about):

1. "Is the multiplayer mode of freelancer heavily populated?"
Depends on which server you join. It is pretty easy to find a server with a lot of people on it. But its not like Earth & Beyond, or a MMORPG where everyone plays in a huge world with eachother, you are confined to the server you pick, and your character stays there (you cant transfer characters between servers )

2. "In some games its almost impossible to find a server thats not running a totally weird mod, do most freelancer servers have mods attached, and all they very different from the original?"
Theres only a few servers that are running mods, but on most servers it is possible for an admin to allow someone to use a modded ship.

3. "What hapens if you die while playing multiplayer?"
You blow up, and you lose all cargo that wasnt equipped to your ship (like spare guns, commodities, etc). You are then sent back to the last base that you docked at.

4. "what happens if you kill somone in multiplayer who is a real person?"
The same thing happens to them, and if youre lucky, they might have had some good cargo which they dropped (which is what player pirates strive for). But theres no PK rating or anything.

5. "is it posssible to talk to anyone in the galaxy who is a real person in multiplayer?"
Yep, theres a system chat (which just sends your message to the people in the same solar system as you), and you can "whisper" or "message" anyone, no matter where they are.

6. "Are there any freelancer clans that I could join?"
There are a few clan leaders and members who post here on the forums.

Thanks so much, I'm hoping someone will give me some clan websites though.