Ok...there will be many other responses, however I will do my best.
Yes...The power Venter will run 24/7
No....It should not run at high speed.
It is my understanding that the Barometric Damper should be set in conjunction with the speed of the power venter. You need to get yourself a Manometer (There is a Manometer Loan Program on this site http://nepacrossroads.com/about2727.html?hilit=loaner
). The reading on the Manometer should be about .02-.03. When I set a power venter up in the past I was able to lower the speed on the venter down to get this number, and I was also tweaking the damper as well.
There are lots of posts on this site on how to set this up.
Here is onehttp://nepacrossroads.com/about7389.html
Keep looking...Use the search function.