If you don’t seal the wood before painting, the water in the paint will raise the wood grain, giving you a rough finish. Wood crankbaits live in a tough environment and many of us want to make them as durable and waterproof as possible, so it is preferable to undercoat/seal the wood with a tough waterproof coating that serves as an added protection against water intrusion. Various products including epoxy, MCU like KBS, UV cured polyester resin like Alumi-UV etc can do that. I use Devcon Two Ton epoxy as a topcoat on many baits so it simplifies things to also use it as an undercoating. Scuff the gloss off it before painting to improve paint adhesion. Some like and use primers. I don’t and have never seen the advantage if you paint with water based paint. Here’s the thing: an acrylic paint finish will last exactly as long as the topcoat you put on it lasts and no longer. A wood crankbait body will last exactly as long as your undercoating and topcoat keep water out of it, no longer. If your topcoat gets damaged, acrylic paint will absorb water and push the topcoat off the bait but the lure is salvageable as long as the undercoat remains intact. So one of the simplest durable finish regimens is epoxy then paint, then epoxy. Or epoxy, paint, then MCU.
Glitter. There are many ways to use glitter and a recent thread goes into different ways to apply it. Specific to your question, if you put glitter into your KBS and the finish turns out smooth, there’s no reason to apply anything over it. If it’s rough, you can simply add another coat of KBS, or whatever topcoat you want. I’d stick with the KBS.
MCU’s including KBS contain solvents that are not always compatible with just any ole other solvent based coating. If you want to mix them, it’s an experiment that may or may not work. Epoxy will almost always be compatible with any other coating because it is more or less chemically inert after it cures.
As far as Createx vs Wicked vs Auto-air, I’m sure there are chemical differences but for our purposes, they all shoot the same and are compatible.