Let them think of it as a rite of passage. If they survive through the weak times they get incredible power.
Exactly. And the cleric and the magic-user will need to do some hand-to-hand combat if the party is to survive, in my experience with AD&D.
I do advise you to pick up the AD&D PHB, DMG, and Monster Manual. Best game books every written -- better than Basic, much simpler than later editions, tons of great material written for it.