Question 1: If you test at the same time each morning, then you will be able to compare and see if things are getting better or worse.
2: There is no need to test at one hour AND at two hours, though sometimes it can be interesting. You have found that you are highest at two hours, so this is perhaps the best time for you to test and to alter your diet accordingly.
3. That's life. You may have eaten different things earlier on, you might have been more active, many things will affect how you respond and how quickly you digest food.
Sally