On your first two points, time is just numbers to Thais and nothing else. As an example, last week I showed up at the hospital at 11.30 as directed to in a letter given to me a week before, to check my eye after cataract surgery. I arrived at 11.15 and the doctor had already left.
On the other hand, yesterday someone said he would come at 4 to replace a glass door, and he arrived on the dot.