Bruce Hoadley's book on identifying wood, or one of the Petersen's Field Guide to trees would be your best bet for identifying the trees. Perhaps also the local Forestry Service office or agricultural extension service office can help.
As for hewing, most hewing is definitely done on green wood. It is much easier. For contrast, ask Dave Dauerty, hewer supreme, about the white oak log that we used in the base of the trebchwt. It had been on the ground for about 5 years and had started to dry. Dave says he felt like a cartoon charachter as the vibrations went back up the ax handle when he struck the first lick. Green's the way to go.
