With Drupal 7, is there a way to either

1. Automatically remove role A when role B is assigned to a user ?

or

2. Assign weights to roles, so that features associated with role B are executed before those associated with role A?

Thank you for any information!

Comments

The Rules module will help

The Rules module will help you out with the first one. You can set a rule on event "Before saving a user account" that removes role B if role A is not assigned.

I'm not sure what you are trying to do with #2, but you probably can't accomplish it the way you think. Roles are not applied serially and are cumulative. Modules and core normally don't even check roles, they check permissions which users get trough roles. So, I'm thinking you'll have to find another way, but it you post more info about what you are trying to accomplish maybe we can help.