Looking for the right modules for user group management I am creating a site that works similarly to Groupon with D7, and I am having trouble finding the right modules to deliver the functionality. 

I need to create different user groups: buyer and seller. 

For the buyers I need to store their name, geo-location, and email address. 

For sellers I need to store the name of their business, email, geo-location, and I want the sellers to be able to create a list of offers(nodes) linked to their business. 

My initial thought is to find a module that enables custom field for user profile. I also need a separate registration &amp; login page for each group, and assign new sign-ups to the appropriate group ( buyer vs seller) based on which page they use to register. What modules would you recommend in order to fulfill these requirements?
I would suggest to manage this by using roles. 
Create two different roles: Buyer and Seller
As both roles have the same mandatory fields, it wont be an issue for you. Additionally, you can customise additional fields and rights for sellers.