As has been said, just about any wood will work.
I'd stay away from 1/4" stuff, though, 1/2" is better, 3/4" is pretty typical for control panels, esp if you'll lean on it, bang on it while playing etc.
For the cab sides, whatever you want, YOu'll likely go thinner on the sides to save weight. Ply, Luan, thinner MDF, all would work, esp if you frame things internally.
If the sides WILL BE structural (and in many cabs they are), you might want to go with thicker ply or MDF.
Soldering a CP, connecting the wires etc isn't anything to shy away from. It's pretty easy once you get going. Might take a little while, that's all.
If you throw in RGB lights everywhere, that gets a little more crazy, but again, nothing to be afraid of.
Good Luck and have fun!