Vermicomposting makes use of earthworms during all or most of the composting process. The most commonly used species are Eisenia Fetida and the closely related Eisenia Andrei. These species have all the desirable characteristics most commonly needed for vermicomposting. They thrive at high population densities. They eat rapidly. They reproduce quickly. And they tend to stay mostly near the top of a worm bin; eating their way up as they are fed, and leaving their castings below.
Worms can coexist with a tremendous variety of micro and macro organisms in a vermicomposting operation, but they need to be the dominant organism. Proper moisture and careful feeding help keep worms in charge of their ecosystem. Worm bins containing E. Fetida and E. Andrei should be kept as wet as they can be without water dripping from the bottom. The worms of course need to have enough to eat. But overfeeding allows other organisms to take over. Fortunately, a significant range exists between underfeeding and overfeeding. So neither case is a common problem.
Most feedstocks will need some kind of processing. Manure should be aged or partially composted before it is fed to worms. Reject produce, kitchen scraps, restaurant waste, yard waste, and food processing waste can usually be vermicomposted without any precomposting, but might need to be sorted, washed, ground, and/or mixed with high-carbon bulking materials.
When partial precomposting is called for, it usually only needs to be done to the point where the materials have become black and sticky. At this point, the compost is still well within the bacterial dominated stage. Compost type earthworms thrive in bacterial dominated compost. Bacteria are their preferred diet. Worms however are selective in which bacteria they consume. Worms eliminate pathogens while actually nurturing certain beneficial bacteria.
Production is related to temperature and population density. If you want to create lots of vermicompost, you need to keep the worm bin warm. And for another obvious reason it is extremely important to know how to keep it from getting too hot.
If earthworms are not reasonably comfortable, they will simply leave their environment. There is no practical way to confine them. Since light brighter than moonlight is painful to worms, some people use light to keep them down in their dirt. But compost worms love to crawl around on top of their food at night, and will patiently wait until dark to do so. If dark never comes, they will become obsessed with escaping, and will when the power goes out. The best practice for vermicomposting with E. Fetida and E. Andrei, especially in a flow-through bin, is to allow a natural cycle of light and darkness, and avoid digging any more than necessary to check conditions or relocate worms.
Worms are not fond of noises and other vibrations, but they will tolerate them if the combination of duration and intensity is not too severe. Worms will put up with some occasional high-level stress, but they have difficulty adjusting to any kind of constant stress.
The article Vermicomposting Methods discusses common worm farming techniques.
The article Compost vs Vermicompost gives an overview of the incredible superiority of vermicompost over conventional compost.