I have 4 N series tractors, two of which are show tractors and sit much of the year with E-10 in them. You most definitely don't need to coat the carb float with anything.
I always use Stabil in the fuel, and have never had a fuel related issue with any of them. Some of the fuel in the trailer queens is easily a year old, and both of them will fire up and run like new. My work tractors have no issues whatsoever on E-10.
In short, just like any other fuel, if you keep Stabil in it you are fine. If you use the tractor frequently and are constantly refreshing the fuel you can eliminate the Stabil. I keep Stabil in all of my fuel, because I never know when I'll be storing something with fuel in it.