The container is a transparent clip-lock plastic box, on the larger side of small. This cache may involve a little bit of scrambling, nothing especially tricky but please take care!
Closest parking would be the laybys on the B9027 valley road below Cuminestown.
For muggle avoidance, I would recommend doing it in daylight. The area is secluded enough that nobody will notice you during the day, it's only if you go shining torches in the dark that you'll draw attention to yourself. Though even then, the risk is pretty low.