Richard Alpert comes to help Locke, gives him a compass

After John Locke moves forward in time, he goes to the plane and uses a belt to put around his bullet wound. While in the plane he sees more Virgin Mary statues and one of the charred bodies. Richard Alpert pops out of the jungle with a torch and a Dharma first aid kit from The Staff station. When Locke tells him that Ethan shot him, Alpert says "What goes around comes around." When Locke asks how he knew where to find him and that he was shot, Richard says that he told him, or rather he will tell him. Richard cleans Locke's wound and pulls the bullet out. Hell tells Locke that the next time they see each other, that he won't recognize Locke. He then gives Locke a compass and when Locke asks what it does, in another great line Richard says "It points north John."

He tells Locke that he has to get his people back to the island in order to save the island. Richard knows that the helicopter didn't go down with the ship and that everyone made it home. How he knows this is a mystery. Then the bombshell. Richard tells Locke "You're going to have to die John." Locke's reaction to this is the 13th image down.

Locke then goes back to the past, seemingly around the same time as before because the yellow beachcraft is still on the cliff and smoking. Locke then looks at the compass which is not the same one that Richard tested him with as a child (see those screens here).

So many questions here. Why does Locke have to die? How will he get off the island? When did Locke tell Richard that he'd been shot? What's the significance of the compass? Also, does it seem weird that Richard wears reading glasses? I guess Ben did too, but I guess the island has bigger fish to fry than taking care of people's optometry needs.