Hi,
Are we planning to manage the devices using Airwave here? If its just for monitoring a read only user should do. However, if we are planning to push configuration we need to have the credentials for a read/write user.
You can have a read only user for local and read/write for master however, in case you have to push any local controller specific changes from Airwave we would need the priviledge for that user. I would also request you to refer to Controller Configuration Guide on Airwave under Home --> Documentation for a better start.