Yes you definitely should use a barametric damper, its a simple device that flaps open when the air pressure changes. You can see it open and close on a windy day. This will keep the pressure in the stove constant so the wind wont pull out all the heat on a windy day and your stove will operate more efficiently. its about $40-50, just buy a 5" one and attatch it behind the stove into the pipe. Make sure its level and play with the adjustment until it only begins to move when its windy. On the pinched hopper its time to change it. I'm on my 3rd one in 24 years, They last about 6-10 years. When they pinch in you know they have to be changed. A real big pain in the ass to get out. You have to disasseble the stove, get everything out and then remove the hopper thru the glass door. I usually cut the bolts with a dremel and take out 1/2 of the hopper at a time. makes it much easier. The parts are still available at woodmans parts, but they have become very expensive.
I hope this helps you with your Surdiac, Let me know if I can be of further help