Using Scangauge with a 2010 Prius

I've had my scangauge for about 2 weeks and will be getting my new Prius next week. I keep thinking of newbie questions. I have hijacked a couple of threads to ask questions about the Scangauge, so I thought I would start a thread where I could discuss it further.

Also I would like to know in general how people are using the scangauge in the gen III, especially those that have previous experience with the gauge in the gen II. What settings/gauges do you use, how useful you find it, etc.

I expect to use the scangauge to help me learn about how the HSD operates. I am curious to see how rpm varies in different driving conditions.

One of my questions, therefore, is whether the scangauge reports rpm only when the ICE is getting fuel or whenever it is spinning. My understanding, for example, is that the ICE is always spinning above 45 mph (correct?). Will I see that even when coasting?

Also, when connecting the Scangauge to the gen III, do you plug it in with the car in ready mode? If so, do you do that every time you connect it or can you connect it with the car turned off if it has previously been connected and recognized the Prius?

I also hope that the scangauge helps me track the discrepancy between the Prius computer reports of mpg vs accurately calculated mpg.

I figure that scanguage is used mostly to help get better mileage, so I am asking these questions in the Gen III fuel economy section of the forum.