Origin registration and CD key issues. What to do?

Oky so I'm a noob at online games and Battlefield.

First of:

Recently i bought BF3 for my PC. I'm no huge gamer and still a full time student so I play games on my laptop. i5 processor, 4GB ram and stupid integrated HD3000 graphics.. Up till now I could play most games on decent medium graphics.. From assassins creed to skyrim and BFBC2 cracked version..

So after 2 hour installation and the 4.5g 8 hours long update the game gave an error at the first loading screen.. After plenty of googling I found that battlefield 3 doesn't support Intel HD graphics..

SO I got over it and decided to go back to BC2 and get the genuine game to play online. My friend play BF3 online a lot and own BC2 so told me I can have his for free. He installed it but never played it online.. But now after I installed it and started to create an EA account they say the Serial key have already been used.

So now me and my friend try to figure out what to do to get his account details. And now I want to give my BF3 to another friend since I can't play the game on my PC but then obviously he must then play on this account? Right?  Luckily its a new account.

So Questions:
1.) How do you retrieve an account without any details and ensure that someone can re-use the serial key of the game? Can't I just give someone the serial key to retrieve the account details or

2.) How to delete the account and get the ability back to use the serial key and just start over from the beginning?

3.) Or how to I get BF3 to work on my PC then I don't need to worry about the rest?

Since now My friend will have to play on my BF3 account. I hope He can change all the details like email address ect. And I have to play on my other friends BFBC2 account which he never played on..

Thanks guys