Interesting techniques all around. I have since my teenage years just gone with decals sliding off the paper onto a glossy surface, take the excess water off the top with a moist towel, and finally use good old fashioned Solva-Set. A brute force technique no doubt, but it works well. Once the decal dries, I pop the bubbles, if any and hit it with conservative amounts of more Solva-Set. Upon final drying I apply a dull coat, or other coat depending on what I want the final model to look like.
Then as suggested above, I will apply weathering and if using chalks I will apply another coat of finish to keep the chalks in place. Old fashioned but very simple.
For old decals, I have either applied a gloss coat to them prior to use or I sometimes scan them and trace them in the computer. That is a pain in the you know what though.
Good luck!
