What is the best possible way of adding users to Queues and Groups given that there are a number of Queues and Groups and a number of users belonging to them?
Where possible, add roles or public groups to queues, not individuals. That way it's easier to see what patterns of access are allowed. It's also much more efficient to add a person to one group than to add a person to many queues. If your access scheme is well-designed, your groups will have multiple members and will find use in multiple queues.