Sorry, in answer to question 1 yes that is correct, and then if the call passed over to the following day and was closed at 09:30 that would be an hour.
As for question 2 SLA would an amount of hours we need to complete the call in. e.g SLA of 8 hours. No to worry to much on this as it is for our reference only. I can do conditional formatting based on these times. e.g if the result of a call is 9 hours and the SLA is 8 I can show that we missed our quota by 1 hour