We normally use epoxy resin on the tang to hold the scales in place with the pins.
To work with I like cocobolo (although if I am using a belt sander I go orange), striped ebony, Oak, in fact the list is huge so not the best person to talk to about the best wood, but I would say that the denser hardwoods are pretty good.
Generally the wood that is used for scales will be seasoned in some cases they are Kiln Dried.
I wouldn't try just any bit that is lying about as I wouldn't know if it had been seasoned, which in turn could cause warping and shrinking of the scales once fixed to the knife.