Miyard has a little beach right across the street where I swim almost daily when I'm there. There are multiple places to access the seven mile beach. Many places don't mind if you hang out on their beach chairs if you are buying stuff from the bar and behave yourself.

On the cliffs, Xtabi allows folks to swim, as well as other places.

On the cliffs, Blue Cave Castle is an affordable place and great clif view.

From Treasure Beach to Montego Bay is probably 2 hours. I can't remember exactly.

Six days in Negril would be fine. I may be biased, but Treasure Beach gets a little boring to me after a while. After a few days I long for Negril. In Treasure Beach things shut down pretty completely fairly early, but for a few rum bars. There are not that many dining options. The beach has waves, which Negril does not, but it is not a long beach, and the sand is not nice and white. When I go to Treasure Beach, I bring along some provisions as the grocery store selection is pretty limited.

In general, it is safe to walk around at night. As a woman, I try not to walk alone at night anywhere, even if it seems safe. And drunk stumbling in the late night hours might make one vulnerable. The key is to use common sense.