Paint for stencilling is very thick, almost a solid. You apply it with a stenciling brush that has bristles only about half an inch long. This is to allow you to blend colors on the work and not let the paint under the stencil. It's kind of like dry brushing but just to the limited area. Liquid paint will bleed under the stencil.
I would probably spray on a real light mist of a clear lacquer and then another slightly heavier coat to hold the stencil paint. Then, you can apply water or oil based poly as a surface protectant. Make the poly type that you use compatible with the type on the table and don't worry about the lacquer or sanding it. If you have a choice, use gloss poly for everything and switch to a satin finish for the last top coat only.