I've learned quite a bit in the two years since I first commented on this thread and thought I'd share some of my current thinking.
First, there is clearly debate over whether or not the leachate is good or bad for the plants. In my opinion, this depends on what you're composting. If you're only composting vegetable/plant matter, I do not believe there are any issues with using the leachate. However, if you're composting animal waste (especially from carnivores!), I would not use the leachate or compost until fully composted. That being said, the next thing I learned was that, if the worm bin is managed correctly, there should be very little, if any, leachate at all.
My worm factory, which was left outdoors, got infested with fire ants that literally attacked and killed all the worms in the bin. Since then, I've made my own bin using three inexpensive Sterilite 15 gallon totes I store in the garage. The bottom one has two bricks in the bottom to support the top one (or two) and provide airflow. The two that go on top have lots of holes drilled in the bottoms and around the top-sides for aeration. The lid that goes on the top tote also has lots of aeration holes drilled in.
I did not put any drain in the bottom tote and have very little, if any, leachate accumulating in the bottom.
Because the totes are larger than the worm factory bins, it does take longer to generate a batch of castings, but the system supports much more worms, so can process much more waste and, I anticipate, once it gets more populated with worms, will process the larger bin just about as quickly as the smaller bins.
Two more things I've started doing just this year (speaking of the addictive nature of maintaining worms!)...
I've been making my own dry worm food to help provide the grit they need for their gizzards and also manage the moisture. I grind up eggshells with things like dry pinto/kidney/black/red/garbanzo beans and add some cornmeal. I'll store this in a jar and "sprinkle" some in the bin and/or mix in with their other food.
Also, when I pulled out my HUGE collard greens plant a couple of months ago, I took all the leaves and blended/pureed them down with water, then added some of the dry food to get a "pasty" consistency, then I froze the mixture in some containers and chopped (literally with a hatchet!) into some chunks that I use as "popsicles" for the worms on the hot days here in the South Florida summers to help cool the bin and add to the food. When I add one of these, I make sure to place it on some dry shredded paper/cardboard to help soak up any excess moisture.
I hope those additional tips help! ;)