Hey there, Fred.
We all use different approaches for these techniques. I'll share mine with you.
A "wash" is a technique that allows you to put subtle "shadows" in your model. Its a mixture of oil paints (burnt umber and prussian blue is what I use), primarily, and paint thinner or some other thinning solution. The oil paint is thinned down in a consistency just enough to allow the oil to "creep" in between seams, panel lines, creases, and other details.
"Dry brushing" is quite literally using a wide brush to apply almost dried paint (usually in a color lighter than the basic paint hue of the kit) to weather the model and highlight the edges. Sadly, my experience is that a brush used for this purpose deteriorates over time. Pastel chalk is used for the same purpose. It could be ground to powder and drybrushed, or applied directly onto the edges of your model.
You might want to consider getting an airbrush and compressor rig. I dare say there really is no substitute for it. There are several advantages. Paint can be applied more evenly, and in far narrower areas than a spray can. Plus, it is cheaper in the long run.
I use a toothpick too. But yes, paint tends to dry quite quickly. But there are just some areas you cant reach even with the smallest paint brushes. But patience is indeed a virtue, and Im sure youll get the hang of it.
Hope this helps!