In my games I actually tend to handle both villian and environment turns whenever we actually get together and play, though it’s because I am the most experienced with it and know how the flow usually works.
As for hero turn if I am playing solo or with my wife I use a random selection (if my computer is on I will use Spiff’s randomizer) and the turn order is just who was choosen first in the order. Now if I play it with my gaming group we tend to just say “who wants to go first?” then proceed clockwise around the table.