Having your buddy who works for dnr view your land and teach you how to ID trees and shrubs will be a great resource for you. If your woods is a big downed trees tangle you might want to clean it up some, but I wouldn't make it so cleaned up it looks manicured, downed trees are part of the habitat. You may want to ask your friend to recommend some leaf, bud and bark reference books and a leaf and bud key that you can use to teach yourself. Sounds like you are going to have some fun managing your land.