Definitely set up a dining hall down there. You probably also want bedrooms for all the smelters and smiths (and assign them specifically). I've recently had a fort with the forges/smelters at the bottom and everything else up top. You spend a lot of time looking at idle smelters with the green A telling you someone has taken the job, but there is no one there, because he's on his way down.
And he probably stopped to pick up the chunk of heavy ore that was closest to him when he started the trip, so he'll be moving slowly. So linking your ore stockpiles (which should be next to the smelters) to the smelters will also make things quicker.
Might as well burrow them all down there, while you're at it. I think it has been reported that dwarves will sometimes decide they want food or booze that is on the other side of the fort, rather than the stuff that is right next to them. I'm not 100% sure that a burrow will prevent this, but it might. I know a dwarf won't accept a job outside his burrow, but I'm not 100% sure if they won't try to grab materials from outside the burrow (but I have a hunch someone will let us know).
With food, drink and a bed down there, and a burrow keeping them from going elsewhere, you should get good productivity. Maybe stick a non-denominational temple down there, too. I think that should cover most excuses that they'd have to ever make that long trip up and back down.
Now you'll just need a bunch of haulers to carry the food/booze/ore down and the crafts and whatnot back up.