1) once a month at least completely replace the substrate.. pick out 'piles' as you see them.

2) once a month when you replace the substrate

3) I use disposable water dishes so I give them a new one with fresh water every week. If the snake fouls the water, disinfect the dish. Disinfect at least weekly.

4)bleach is nasty stuff.. go to mgreptiles.com and get chlorhexadine solution. The stuff is completely safe for animals and is a great disinfectant.