I do not know about faclities at the park but the ride out is pretty easy. No serious climbs, justa sustained 2-3% grade for about 6 miles once you're 6 miles in from the Banks trailhead (the climb starts just before Buxton). I haven't been far past Stub Stewart yet. I don't know if the trail actually goes through the park proper eventually or just the 5 car parking area just below the ranger station.
The trip out from Hillsboro is covered in another Bank-2-Vernonia Trail thread. The last MAX stop is the easiest route.