Sorting lists of numbers in pairs and in ascending order

Dear members,
There's these list of numbers I have attached. You will notice that there are duplicate numbers which are representing time (in minutes). Here comes my questions:
1. What formula or function or code can I use to remove all the duplicates in "Time" column and populate the "Time after removing the duplicates" column with unique Time values.
2. I will like to populate the "Difference in time" column with the ascending change in time. For example for this data we will have start and end time as follows: 0 to 1. 1 to 30, 30 to 60, 60 to 120, 120 to 179, and 179 to 180. So the Difference in time for 0 to 1 = 1, 1 to 30 = 29, 30 to 60 =30, etc.