JMHO: Manual , more functional , tilt for shade and slope to drain water. Power; one more thing to go wrong.
I've had both vinyl and fabric , maybe wishful thinking but I think I'm cooler under the fabric.
Install , because of the weight , will require help with the tube and some heavy duty ladders.
Length could easily be determined, and limited, by the availability of good structure in the wall to mount the brackets.
Haven't had to purchase one so can't help with price.
Find a similar unit and take measurements and pictures.