A standard servo should work for the throttle. What radio are you using for the plane? From what I have read you need to set up a failsafefor gasoline engines. That would mean a PCM for 72Mhz or about any 2.4Ghz. The copper or aluminum on the firewall is for interference. Minnflyer knows a lot more about running gasoline engines than I do, so it may not be necessary. Just do a range check both without the engine running and with, and if you get interference with the metal shield would be necessary.

If that is your version of a vibration mount in post #13 you will also need rubber bushings behind the firewall under the flat washers. Also make sure to use nylox nuts so they won't vibrate loose, because with the rubber vibration damping you don't want to tighten the bolts down much more than snug.

When you hook up the kill switch with two modules the kill switch goes in front of the firewall, and the sender goes behind the firewall. They are linked through fiberoptic cable which will not transfer interference.