Supplier self service security questions

Hi All

Can I get some answers to the below questions on Supplier Self Service

a). How is the security setup for Supplier Self Service.

b). How do we ensure that Suppliers cannot cross information i.e they cannot see other suppliers data

c)  Is what the supplier can view part of the security on the portal? -

d). Is there a supplier registration process? How else is log in information passed on to suppliers

A quick response would help

Thanks

Govind