couple questions about the membership plugin

I've gone through the videos and have a pretty good feel for the plugin, but have a couple of questions. The site I am creating is an Intranet site for an organization, so there will be no payments required and no visitor access allowed. we have 2 levels of access set up on the site Associates and Supervisors. I have associate set up as the lower level and then there will be one section of the site and one category that are dedicated to supervisors, that I would like to hide from the associates.

- I would like the supervisor resources to be completely hidden from the associates. Is there any way for that to happen? I seem to be able to have them redirected to their login or account page, but the menu items and widgets show up.

- I will be migrating about 200 users from another site (also using the membership plugin) over to this new site. What can I do to keep the username and password for all the users that same so they don't have to login again?