Subject to/Lease option question

[Kevin Craig]

If I buy a house for 100,000 and sell it for 120,000 and charge a buyer 5,000 down to get into the house. How is that contract structured?

Does he begin a new contract for 120,000 after the time period comes where he can excercise the option or does he keep paying the normal rent?

If he enters into a new contract for 120,000 what happens to the old one and do I get 10,000 right then and there when he enters into the new one?

Thanks in advance for all answers..

All answers appreciated..