Atomic operation on queue

I should implement a class in Visual C++ with a queue; in this queue I've to do atomic operation. Searching on the web, I found the class std::atomic , but I keep some questions. The first is: what's the difference among:

A) atomic <queue <T>> fifo;

B) queue <atomic <T>> fifo; ?

The second question is: how can I make atomic operation like push?

push (T.load) 

is the right solution?

The last question is: if I protect some operation on a queue with a mutex, still I have the need to do atomic operation on it?

Any advice is appreciated, Greetings