"Anyway, the Others defend the island against intruders, including the Army guys with the bomb, but when the Others are banished from the island, like Charles Widmore and Eloise Hawking, they age in real time."

Charles Widmore and Eloise Hawking DID age on the island. They showed them in their early 20's the first time we saw them. She was "Elly" with the gun when Daniel saw the bomb hanging there and told her to bury it.

"The new Locke didn't seem to know what happened between Ben and the smoke monster/Alex, so I don't think the nemesis is the smoke monster."

Of course he would act like he didn't know what happened between Ben and "Alex"! The smoke monster as Alex told him to do everything that Locke said. He was "convincing" Ben to listen to Locke when he would eventually tell him to kill him.

Rose and Bernard had gone back in time along with Sawyer, Juliet, Locke, Miles, Dan, etc. Every time they were "flashing" around, Rose and Bernard must have been too on some other part of the island. They were back in the 1970's too, but chose to remain alone in the jungle away from Dharma and the Others.

That many-masted Galleon is the Black Rock.