I haven't been to Kokadjo lately - are Fred and Marie still running the combination general store, bar, restaurant, cabin rental and game check place at the end of the paved road where First Roach Pond spills into the Roach River? They are a real pair of characters, known statewide and beyond among flyfishermen.
When you're driving north on 201 into Jackman, about 10-12 miles south of town there's a turnout/rest area with some spectacular views. Take the time to drink it in - if you hit the weather and week right, the colors will make scenery that's otherwise spectacular into something to make your jaw drop.
Last time I was in Jackman the gas station at the top of the hill south of town closed at 5. IIRC, the little supermarket in the middle of town closed at 5 or 6. Having a cooler full of casseroles prepared at home, as suggested above, is a great idea.
While it varies across the state for reasons no one seems to know, best estimate was we had a periodic high in grouse population in 2011-12. It's been coming up the last couple years and should be good this year, though that's a long way off. There's still a lot of snow in the mountains and up north (and we're supposed to get a little more tonight even in Portland).
Driving up from PA, you will be able to stop in Freeport at LL Bean's main store. It is just off 295, which you would pick up just before Portland. Unlike all their other Bean's stores (which pretty much carry only clothes and a little outdoor equipment), this one is a serious hunting and fishing store. There are no locks on the doors - it's open 24/7/365. If need be you can get licenses and ammo there (and anything else you might need, including long guns). For those with older shotguns with short chambers, they are one of the few places in the state that carry RST's short-chamber rounds.
If you fly fish you may want to pack a fly rod and flies. It's possible waters near where you hunt may be open - this is a matter under discussion in Augusta at present.
We look forward to you coming up, having fun, and enjoying what Maine has to offer.
"A man's rights rest in three boxes: the ballot box, the jury box, and the cartridge box."
Frederick Douglass, speech in Williamsport, November, 1867.