No they will be open at startup because the vacuum needed to hold them closed will not be there. I suppose you could install an additional switch to trap the vacuum before you shut off the car or some sort of reservoir tank. In reality they close pretty quick after the engine starts as can be seen in the video.
Function is dependent on engine load and not rpm.
Adding the mechanical vacuum switch just allows you to shut off the vacuum being sent to the muffler valves and 1. have them open all of the time or 2. force them open when they would normally be closed and you want a little more noise, for example idling at a stoplight. I think the function is similar to the M2W which is a remote activated electrical switch used to cut the vacuum instead of the plunger type mechanical switch used here. Maybe someone who has the M2W setup can comment on its function.
Hope this helps.
http://youtu.be/nxr-Nou58Ug