Registration of Suppliers - maintain logon/passwords

My client wishes to use Registration of Suppliers - can I request assistance where possible with the following queries?

As interactive forms get passed between client and their potential suppliers, this is through e-mail, is this correct? At what stage do we have to maintain a URL for a supplier with his own id and password.

My client is interested in functionality ROS gives, but does not wish to maintain user-ids and passwords for each supplier where possible ~ any relevant advice useful.

Am I correct in saying that seperate user-ids and passwords would need to be maintained for each supplier, and if so where is this done (in the vendor group area on SRM 5.0?)

Thanks in advance, much appreciated!

John