Im thinking that maybe richard once died and had to be brought back to the island, and now he doesnt age. christian shepherd also was on the island once and when his dead body was brought back he came back to life and will no longer age. I think locke will be the same when he is brought back... just a theory
Think Jas0n might be on to something here.. Maybe people that die in service of the island then become part of it and come back as a manifestation of their former self at the age of death.. Would explain why Richard had no fear of Kate shooting him when she had him point blank..
I don't think the healing ability is limited to the island as Locke ends up back on the mainland and apparently goes to see the O6, yet no one makes mention of him being in a wheelchair.
I don't think Ms. Hawking is like Richard, but rather hopping about in time @ her current age.
I thik Richard had no fear of Kate shooting him because he had all of the Others in the woods with guns pointed at her.