As you can see...different strokes for different folks!
I'll throw another one atchya!
Obviously, #1 is a good gloss coat, before your decals.
....I use Minwax clear gloss lacquer (basically the same as Testor gloss). I'm assuming you have a rattlecan. Spray a couple mist coats first. If ya get too heavy, too quickly...it'll wrinkle the paint underneath. I have had terrible luck with trying to use Future as a gloss coat...but there is a great use for it.
#2, "Set" is meant to go on the model, then the decal placed over it, while still wet. In my experience, even with a good gloss, I still had issues with "silvering". I have filed my "set" (micro-set) in the round bin under my bench. These days, I pour a bit of Future into a small plastic cup (like what you can get at McD's for ketchup). When the decal is ready to place, brush on a little Future (just where the decal is to go)...place decal, dab away the excess as you normally would. Sometimes, you'll get a little leftover residue...you next clear coat will make that disappear. After decals sets a couple minutes, brush on a little "Sol". This softens the decal. Some decals will wrinkle, but tend to go back to normal...gotta learn to just ignore it, DO NOT mess with it!!! Some decals will need several applications of "sol"...and some are almost completely impervious to the stuff ***cough***Tamiya, Academy, Hasegawa***cough***.
#3..decals done, set/cured...Another gloss over the decals is not a bad idea...followed by a "wash"...if you do such things.
#4..Dull coat