Partnerships - tracking sign-ups from customers of different companies

I'm going to be partnering with a companies who will be sending traffic to my website, and giving them a percentage of sign-up monthly fee. For example, company A may have 5,000 rewards members. Company B has 10,000 reward members.

1) Using a code of some sort I want to track a signup from from a reward member of company A, versus company B?

2) I want there to be a to prevent two multiple people of using the same code. Example, a person from company A giving there code to someone else to use? This is like fraud.

3) I want there to be a way to see/track rewards members from company A, B, or C, so that I can write this partner a check from the total number of there members who sig-up. For example, they may get 20% of $5.