re: what's the right choice of wood.

It depends on what you are building. For flat panels that will be painted I think MDF is a good choice. Cheap, flat, doesn’t require sanding and takes a paint finish better than just about anything else I can think of. For wood, I suggest you use a close grained wood that is not too expensive. I agree with Shipwright that alder could be a good choice because it works very nicely and planes/sands to a buttery smooth surface. It carves nicely too. A great wood that is way underused in my opinion.