The natural environment for a worm is happily burrowing through the fertile ground or hungrily digging through a local manure pile. Putting them in a box and then harvesting their castings is not natural. They do adept well to a composting environment if the worm composter follows a few basic rules.
If your bin has too much wet green waste it will start to produce nitrogen to speed the breakdown. The nitrogen combines with free hydrogen and the result is ammonia, a highly pungent chemical the smell of which will burn your eyes and sting your nose.
The cure is simple. Cut back on the food, remove the old food and add more bedding to absorb the liquids. When adding new food material add it deep in the bedding. The bedding will help absorb some of the odor and it will keep the food smell away from predators.
Worms leaving the bin will be caused by the conditions not being right for them in the bin. First check the holes in the bottom to insure that the bin is draining properly. If the moisture seems alright, the bedding may be too acidic. A common cause of this is citrus peels or other acid food. The cure is to add some garden lime and cut back on the acidic treats.
Always bury the food in the bedding to keep the white flies from having contact with it. If that doesn't work try covering the bedding with a sheet of plastic or some old carpet. Spiders are great white fly catchers and eaters. Encourage a few to take up residence in your bin. If all else fails, move the worm bin to a place where white flies will not be a problem.