website script modification - PHP / MySQL

I recently purchased an "incentive" based website script. Right now when a user signs up for an account, it doesn't require their address. This is what I need done -- On the registration page, I need it so that they have to input their home address, city, state, and zipcode. Right now the script has it so they NEED to input their paypal address. I would like this changed so that the user can choose between a check or paypal payment option. If the paypal option is selected, they must input their paypal email address. Also on the member's homepage, I would like it so that the mailing address is shown on their page. Also, there will need to be a "change address" button so that if they need to change it, it can be done. The most important thing about this programming is that all of the new features comply with the admin panel. On the admin panel, I have the members user names. When I click on that, I should be able to see their mailing address, etc. Whoever gets the gig MUST have some sort of IM either Yahoo or AIM, so that I can discuss in further details. Once the bidder is selected, I will send over all of my script so that it can be edited. Thank you!