In all honesty, I'm not terribly certain what to do about caverns. My fortresses typically don't take me very far down yet. I've encountered a few and have so far let them be.
Is there a general "cavern help" thread someone could bump?
I generally don't deal with them. I make 10 z-levels of up/down stairs in a 3*3 formation. If I get a cavern I cancel digging on the z-level under that, and look at the terrain. Most of the time there'll be a pillar I can continue the dig-straight-down strategy in, so I wall off any cavern entrance my guys dug and sink my next 3*3 up/down stairs shaft there.
It's actually pretty simple. Just dig straight down, then when you break a hole into the caverns pretend your guys did the same thing above ground, and wall it up the same way you would if you were worried about parrots invading instead of flying Hungry Heads. Then plan a shaft just like you would if you were digging stairs to the top of a mountain.
I usually do this as soon as I arrive, so I don't have to deal with Forgotten Beasts, and I almost always build a staircase right through the middle of the cavern. It's risky while they're building it because any f;lyer can fly up the stairs into your safe area, and when you get to the cavern's ground level anybody can walk up (I once had a troll do this, before I had any weapons, it took all seven guys to take him out and he killed two), but it really saves on dwarf walking. Otherwise they have to go 30 squares out of their way to get around cavern 1, 30 more to get around cavern 2, etc.
But if you've waited you probably have some flying FBs waiting for you (they start appearing at 20 dwarves), and if you've never dealt with caverns before you should avoid that.
Losing is Fun, but why start now?
Nick