Ok, I totally hate touching the roaches so I don't really separate mine too much like the youtube vid showed. I keep the egg flats in their enclosure and i take one flat out and shake it into a large empty tote. Then I dump them from the tote to a small shoe box size plastic container/tote that I keep by the lizard tank for feeding out of. Then I grab the feeders with tongs. Sometimes I'll knock a bunch off into a bowl for her to chow down on. But My Dragon only eats about 8-10 every other day, so the tongs work pretty well.
When my colony gets too big I lower my price on my Amazon.com add for them. If I post them for about $20 for 100 mix they sell really fast. Then I use my same approach for the feeders and box them up for shipping. I don't make a ton of money this way, but I get a little bit, and my colony never gets too big. If I sell off enough that I feel more comfortable with the colony size, then I raise the amazon price.
As for what to feed them. I give the roaches in the small feeder box a diet that I bought from my exotic vet. It's the T-rex calcium cricket gut load and fluker's calcium cricket water. The colony gets a mix of chicken feed, tropical fish flakes, turtle food, and calcium powder. They also get miracle grow water crystals and treats from my kitchen (Right now 1/2 can of cat food).
For heat, I keep my roaches in the basement. Outside temps in my area are about 45 during the day and at night lows in the 30's. So I am running 3 small heat mats (2 zoo med brand and 1 pet smart great choice brand). During the summer I only needed 1 small zoo med heat mat, but over the fall and now winter I have had to add more heat. I ran the great choice mat on a timer and had it only on at night for a while, but now that the lows here are so low, I need to run all 3 all day and night. Depending on where I put the temp prob on my digital thermometer the temps are about 77 in the coldest spot and 108 in the hottest corner. I use a 10 gal glass aquarium with Styrofoam and plastic insulation.
2 small zoo med heat mats are stuck to the bottom and the great choice is between the glass and the Styrofoam along the back.
I hope this helped.