1. after every layer of paint or chalk, do I have to add clear coat?
Paint, probably not. Chalk, probably. The chalk will continue to move around until you fix it in place. I'm not suggesting that you use 1 color, spray it, use the next color, spray it, and so on.... but You'll get to a point where you'll want to give it a spray coat and see what you end up with before continuing.
With acrylic paint, unless your next planned step involves something that will remove the paint (like something diluted with alcohol), its pretty well stuck on when dry.
2. When adding shocks or powders over the paint, do I add them while the paint is still wet?
Generally, let it dry. There is a technique where you mix the chalk INTO the paint and then apply it. But applying it into the paint after the paint is on there just sounds like a recipe for a mess.
3. What would you guys recommend when it comes to mixing the acrylic paint and water(ie what ratio) or do I just add a little bit of water at a time until I get the consistency that I’m looking for?
The more water, the lighter it'll end up being. There's no golden rule here. You want the paint to run, but how much water will govern the final effect. One word of caution... using straight water will cause the paint to pool at the bottom edges of things. When it dries, it'll leave a "watermark" of paint. Put a little alcohol in it to break up the surface tension, or be prepared to wick the bottom of the panel with a paper towel to prevent that from happening.
Theres many ways to do it. if you're messing with a "throwaway" car, then there's no wrong way to learn. Just make sure you work top to bottom... it never rains up.
