First, make sure the crib rail is down so that he doesn't fall. If he can get out anyway, it's not going to help him get out any more than he already does.
We also tried the baby gate in the doorway until our son learned to scale that, too. When he was 2 1/2 we moved him to a big boy bed, but in the meantime we put a childproof handle on the doorknob inside his room. We used to shut the door until he fell asleep, but now he stays in bed and falls asleep on his own so we can leave the door open when we tuck him in.
And, as for getting out of the big boy bed, we used the Supernanny technique of just being consistent and returning him to bed over and over. It took a couple of nights but it worked. He rarely gets out of bed anymore. The moms who say you have to teach him that you expect him to stay in bed are right. Just be firm and consistent, it's for his own safety and his own good. You're right, he needs his sleep.
Just be sure that you put a gate at the top of the stairs in case he wanders or sleepwalks overnight, or gets confused while he's coming to look for you.
Have fun!