A. Can I limit user(s) to a specific campaign or campaigns?
B. Can I limit user(s) to view only role for campaign setup?
A. Yes. Setup a non-admin user and then add them to each campaign to which you want to give them access.
B. Yes. Setup a non-admin user and choose "read-only access" when adding them to a campaign.
Here are two simple steps to do (A) and/or (B). First go to Campaign setup page, section 4. Click on "Add Authorized User". Then select the user and decide if the user needs "Read-only" or "Read and write access".
Selct an existing user and define their roel: