CRM 365 - 1) add roles for users 2) Track ownership change between users

How do I accomplish the following:

1. How do I add roles for users which I can use to track progress
2. How do I track ownership changes as a lead progresses from one role to the next

Roles:

1. Lead worker (say, "Victoria", "Johnny", "Anthony")
2. Qualifier, (say, "Brian", "Denise", "Lara")
3. Sales person (say, "Sophie", "John", "Dennis")

The idea is that a Lead worker hands off leads to a Qualifier, who either qualify or dequalify the lead. If a Lead worker qualifies the lead it is handed to a Sales person who either make or break a sale.

Ultimately I want to be able to track any ownership change in order to analyze eventual problems during this "value chain". And also, of course, in order to pay the individual roles some share for their contribution to any successful sales.

Dennis makes three sales. The retrospective chain is, fx:

1. Dennis-Lara-Johnny
2. Dennis-Brian-Johnny
3. Dennis-Denise-Victoria

Sophie makes two sales. The retrospective chain is, fx:

1. Sophie-Brian-Anthony
2. Sophie-Lara-Johnny

That gives us 5 sales with the following roles involved:

1. Lead Worker
   1. Johnny (3 sales)
   2. Victoria (1 sale)
   3. Anthony (1 sale)
2. Qualifier
   
   1. Lara (2 sales)
   2. Brian (2 sales)
   3. Denise (1 sale)
3. Sales person
   
   1. Dennis (3 sales)
   2. Sophie (2 sales)
   3. John (0 sales)

How could I accomplish this?