I once documented the weight difference on two of the same planes I built {Sukhoi} with one using Ultra and one glassed and painted, I don't recall what it was but it wasn't enough to worry about. I used 1/2 ounce glass and Deft Sanding Lacquer Sealer, no warpage and 80% of the weight gasses off as the Deft sets up, very easy to work with. It's great with gas powered planes but I discovered the hard way the Deft isn't fuel proof when a fuel tank ruptured.
I did once build the 60 size P-47 TF kit, it was pretty easy but I have been building a long time. I find very little difference building a small kit or a giant scale as long as you follow the instructions and don't make any major mods.
Framing up a kit doesn't take much time, it's all the finish and set up work that consumes the hours.
Do a search like Bingo said and pull up some of the old build threads. TF makes a good kit and they tried to keep them simple.