I don't have much in the way of suggestions for you, other than that I had to have my hand pump replaced because of it leaking. I didn't really try to find the replacement washers. A local RV shop replaced it while doing some other electrical
work and checking out the propane
system for me on my '99 13 footer. It appeared easy and wasn't expensive. It did leave one old screw hole in the counter top from the old pump visible, but they filled it with a small bolt - hardly noticeable.
Regarding the vent, they are optional, mine doesn't have one either. I do have the small window behind the stove, plus I had the Scamp
factory install a Fantastic Vent in the roof - GREAT improvement. When cooking without a breeze, can just turn on the Fantastic Vent for removing cooking odors, plus it is "Fantastic" (pun intended) for cooling off the Scamp on warm days.
I'm sure you'll have a blast, both fixing up and camping in your new Scamp.