At CAPE Liberty, the security line for handicapped is the far left lane. It's not necessarily faster, but they are accustomed to dealing with wheelchairs and other assistive devices. After you go through security, there are about a million check in desks, with almost no waiting. If you arrive after 10:30, you will probably be able to go directly onto the ship after check in, without being in the waiting section. If you DO have to wait, the section is all the way to the left after check in.
There is an elevator, and either someone there will help, or you can take him there yourself. I would get help because after that point, someone else should push him up the boarding ramps. Anyone in the terminal can radio for someone to do that for you.