3. Not sure if you have any home automation / smart home switches in your house but I will say it is nice being able to turn the fans on and off remotely with your phone or a smart speaker. You can setup automations to redirect airflow to the remote duct kits if the main room gets too warm or above a certain temperature. I use Caseta smart switches which are compatible with Apple HomeKit, Google and Alexa.3. Where does everyone like having their blower switches? I'm guessing mine will end up on left or right side wall. Ironically I have a spare switch on the main bank of light switches in this room that controlled the wall lights on either side of the old wood stove. I wanted to splice onto these for simplicity, but my wife doesn't want the fan controls over with the light switches.
edit: 4. PE manual says remote duct can run a max of 20'. Do people follow this spec, or does upgrading to a higher CFM fan allow for longer runs?
4. I don't have any experience with longer runs but if you insulate a longer run and have a more powerful fan, it should lengthen the distance you can pull heat through the ducts. The specs they list are for their duct kits and from what our installers told us, almost none of the manufacturers make great remote duct kits. For less money than the manufacturers duct kit, I designed my own and it performs much better and should last longer