Here's my theory on the numbers (though I don't yet know how 42 fits):
Forget 4 for the moment, because until last night I didn't get that either.
If you do a translation of numbers to letters using A=1, B=2 etc. then:
8 = H
15 = O
16 = P
2+3 = 5 = E
In the season finale last year, Jack asked Locke what he thought was down the hatch, and he answered "hope." Last night on season two's premiere, Jack's father made a big deal of giving his patient's "hope."
Now, the 4, by the same pattern, gives us D -- could stand for "Desmond."
I don't know if this is relevant or not, but pull that "D" off of desmond, and the rest of the letters anagram to "demons."
It's a bit far fetched, perhaps -- but could it be Pandora's Box somehow?
Hi, Shirley Temple Pudding.