Very fixable. Jigsaw all the pieces back together. Replace wood that's too badly damaged or missing with the same type. Use balsa or thin ply on the inside to reinforce the pieced-in places. If the firewall is too badly damaged to repair, make a duplicate. Cut the wood carefully and make it fit right. Don't rely on glue to fill large gaps - it will be structurally unsound. However, you can use thin CA to soak the inside of the area. This will make the repair very strong. The wing is easy. Use an angled-end splice to replace the LE, and simply lay down replacement sheeting. It looks like you have enough rib there for the replacement sheeting to rest on.

You'll be using a jig or band saw, probably an X-acto saw, and an X-acto knife. Maybe a drill (holes in the firewall. Sandpaper and putty, too. Thin and thick CA.