Q: What is the difference between Abandoned and Rolled calls in Historical Reports for Single agent?

Rolled call (Single agent report) - call in the queue that reached an agent but was not answered by him.
Abandoned call (All Agents report) - call didn't reach an agent and was finished by the caller before it was forwarded to anybody.

Q: Why is the value of Total calls for all agents not equal to the sum of Total calls for each agent?

Total calls for each agent - calls that reached an agent and were answered or rolled by him.
Total calls for all agents - calls that reached the Contact Center group. They could be finished before reaching an agent, timed outed, routed away or failed. Such calls will not be included in the agent's report.
On the other hand, if the call was not answered by an agent for the first time, it came back to the same agent after the queuing and was answered by him - it will be counted as 1 call in Reports for all agents and as 2 calls (1 rolled and 1 answered) in Report for this agent.

Q: How can I see Answered calls for each agent?

Answered calls for each agent = Total calls - Rolled calls

Q: How is Queue time counted?

Queue call flow:
When new call is coming, it is looking for an available agent, if no one is available – call is waiting in the queue.
If agent is available – call is automatically routed to an agent.
If agent does not pick up the call – call is going back to the queue looking for another available agent.
If same agent appears to be available call is routed to this agent again.

Queue time does not count calls that were connected (answered by agent) immediately (but such calls could be in the queue for 1-10 seconds – time when agent's phone rings). So, these seconds are not counted in queue time, but are counted in total call duration time.
For example, Total call duration time is 55 seconds. Talk time is 50 seconds. However, the Queue time will be 0 seconds.

Q: How Calls per hour are counted?

Calls per hour = Total connected calls for this agent/time logged in today by this agent.
The value is rounded. For example:

1.5 rounds to 2.
3.3 rounds to 3.

Value Time logged in today by this agent is also rounded. For example:

1 hour 30 minutes rounds to 2.
1 hour 29 minutes 59 seconds rounds to 1.

Related articles:

General article about Contact Center Express Reports

Active Reports

Historical Reports for All agents

Historical Reports for Single agent