The Missed calls report will analyse your missed calls to see which callers have and haven't been responded to.
The time window in which a call must be responded to if it is to be considered handled is user-definable. It is known as the "call back period".
Yes you can. You can run a report on inbound calls where the dialled number (route) is filled in with the number you are looking for. This can be either the last 6 digits of the number called or the group it was initially routed to, depending on the phone system.
Another way to get this information is by running a 'Frequent numbers' report on 'All inbound calls' to show which route is most commonly called.