As other folks have mentioned, you part outside the group campground entrance. Make sure you do not block the road at all, or part on any bushes or shrubs. Though there is not an official map from the state of the dino area, there are a few maps out there. One can be found on ExploringAllaire dot com
Yes park outside the group campsite entrance and walk past the two gates.
As far as I know yes, that's the only parking area that I know of. Just keep walking straight ahead on the trail,no turns until you come to the butterfly.
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