Best thing to do is probably just to buy another pot and transfer the glue over as you run out. You can theoretically use most non nylon brushes but it tends to dissolve the glue that keeps the bristles in place, so maybe rinse right away? I’ve used blunt syringe tips before with some success just using capillary action.
The white SpeedPaint is actually a runny light grey that shades the panels of the stormtrooper armor. If you’re not sure how well a paint job will work just try it out. If you’re really worried practice on some cheap toys or something and just study how the paint affects them.
Slap chop works best with models with lots of detail to catch the dry brush, but works fine on just about anything.
If you’re going SpeedPaint washes aren’t necessary, they’re essentially a base coat and wash in one step. I would recommend some normal paints to do highlights with. Highlights are pretty tricky with speed paints.
Do like these sculpts a lot. Great paint job. Would work well in all sorts of games.