WHAT THE HELL HAPPENED TO RICHARD ?

Well he was still alive with Kate, Sawyer, the pilot and the psychic guy, so I dunno if he had demons to fight in his afterlife before he could "move on" that prevented us from seeing him in the church?

good point, richard wasn't in the sideways world (limbo). maybe he didn't die yet, but I think enough time passed for all of them to die eventually so I don't know. hummm

He realized he was aging and set up retirement in Boca.

Honestly I have no idea. Trying to think this one out only makes my brain hurt.

Richard was finally able to fulfill his and his wife's goal, 1st to learn English in order to travel to the New World (America) 2nd he did travel to the New World with Kate, Sawyer etc and enjoyed a new life in the New World and since he was able to age with his immortality gone with Jacob's death, he lived a normal life, died and met up in his timeline with his wife :)