RE: Which covering?
I used and continue to use both Monokote and Ultracoat. While they are different I don't see 1 being any easier to use than the other, just follow the directions. As for flat colors my opinion is that Monokote has flats that match military colors better. Flats are no harder than regular Monokote to use. I'd suggest you select the covering by what colors appeal to you the most, follow the included instructions and you should be happy with the result.