Supplier Managment

Can someone tell me,

How can we create the supplier as follows:

a) Pre- Registration:- Only RFQs can be entered for this supplier. (is there any way, other than, checking RFQ only???)

b) Registered Supplier:- Should be available for All Kind transactions (POs, RFQs and Payments).

c) Blocked Supplier:- supplier should be available for returing the goods or making any balance payments, but system should not allow to create new POs against the blocked supplier. 

Your valuable inputs are highly appreciated!

Regards

Jithendra