Only my personal experience here - you chose to do it or not.
On action parts cleaning - instead of WD-40 (nothing wrog with that) I use regular Varsol from Home Depot. Does the job same good - cost 75% less. To fully submerge all action parts you'll need at least quart of it. Brush it with tooth brush - exactly what I do. Then I remove all leftovers of Varsol by compressed air (not from the can -but from Air compressor) - It cleans parts - bone white clean. Than after that - i spray all bits and parts with regular "Brake parts cleaner" from Canadian Tire. And at this point you're ready to lube job. Choise of the lube is up to you. I prefer synthetic gun oil, but most of the time i just spray G96 (two in one - cleaner/lubricating solvent) and it does the job just right.
As of Nitro solvent to remove backed fouling - I stopped using Nitro solvents after someone recommended G96 to me - and I can recommend it to you as well - best cleaning products I have tryed so far.
As of bronze brush

it will sound strange - but I never done it other way - and it works beautifully for me - and I have never done any damage to my guns by doing so.
After spraying some G96 inside of the barrel and lettng it sit for a minute or two.
I put my cleaning rod (with bronze brush at the end) into cordless 12V drill. And just go inside on slow - back and forth about 4 inch increments - trick is to have drill spining in same direction you have your twist. I
never go from muzzle towards chamber - allways from chamber toward muzzle. To do so - put rod (without brush) through the barrel, starting from muzzle. When you see the end of the rod coming from the chamber, screw the brush on and proceed.
After that again i use compressed air to blow out all clean. From this point I do "patch through" job until I satisfied.
Have fun with your SKS - it's nice lill zombie whaker.