How to Manage Role Permissions and Search Custom Post Types

I'm creating an 'Equipment Locator' for a construction company. I've created the 'Equipment' Custom Post Type using WPMUDev's CustomPress plugin. I've added the appropriate Custom Fields to the Equipment post type.

Now, I need two things:

First, I need to assign capabilities to two specific roles I've created. I've created a 'Drivers' role and a 'Shop Workers' role. I've tried using Justin Tadlock's Members plugin, but it seems to not be specific enough for what I need.

I need to allow the Drivers role to create new Equipment posts (ONLY Equipment posts), edit existing ones, and that's it. I don't need them to see anything else on the WP dashboard when they login.

I need to allow the Shop Workers role to edit existing post types - that's it.

Secondly, I need a way for employees at the company to search through the Equipment post type - preferably from the admin dashboard (which would mean that's one other permission I need to give the Drivers and Shop Workers), or at least from a page. They need to be able to search by the name of the post as well as any of the custom fields I've defined for the Equipment post type.

The goal here is the have Drivers log locations and mileage of equipment, Shop workers to edit mileage data, admins to create/manage everything, and everybody to be able to search through the Equipment (preferably from the dashboard).

All help is greatly appreciated!! Thanks!

BONUS: Anyone have any code snippets I could insert to trigger an email to an admin once a 'mileage' custom field ('Current Mileage') for the Equipment post type comes within 50 miles of the mileage number when it needs servicing again (this is a custom field, too -- 'Mileage Next Serviced').