Commercial poultry farms have equipment to take off the feathers, but you will have to do it buy hand. Finally, you need to market your chickens. Supermarkets have contracts with major suppliers, so you cannot sell them there. You can try selling them at a flea market, but you would need a booth.
Antidiuretic hormone (ADH): A relatively small (peptide) molecule that is released by the pituitary gland at the base of the brain after being made nearby (in the hypothalamus). ADH has an antidiuretic action that prevents the production of dilute urine (and so is antidiuretic).
ADH could affect potassium concentrations in the same way that it affects other constituents of urine, in that it regulates the amount of water in the urine. More ADH would lead to less water in the urine, giving you a higher concentration of potassium, as well as higher concentrations of everything else.