>>If it stays anchored off the coast, how are the evacuees going to get on it?
Some likely ways are linked below:
http://www.fas.org/man/dod-101/sys/ship/lcac.htm
http://www.fas.org/man/dod-101/sys/ac/ch-46.htm
http://www.fas.org/man/dod-101/sys/ac/h-53.htm
And I seriously doubt it is "anchored". Freedom of movement is key for a warship in a semi-dicey environment.
Nashville is a large amphibious vessel. It isn't allowed to dock at Beirut Harbor. They first sent out 40 Marines on a smaller landing craft when they arrived.
Then the Marines helped 300 evacuees per trip get on the landing craft and go back to the boat. They did that 4 times to get the 1200 onboard the Nashville and underway to Cyprus.
Saying that was assuming that all went as expected - I haven't seen a report on it.