Hi, so my photo teacher just sort of left suddenly and a new teacher was hired but the thing is he's done all digital and nothing in the darkroom. So basically, I'm trying to teach him and my class the basics (and then some) of the darkroom. I have a couple of questions though: 1.) What chemicals can be reused? Can they be reused for both film and paper? How often or for how long? 2.) How will I know when chemicals have gone bad? What are the typical shelf-lives of developer, stop bath, and fixer? 3.) For a high school class with a limited budget, should resin-coated or fiber-based paper be used? 4.) Do enlarger lights dim over time or do they stay the same until they die out? How do I change an enlarger light? 5.) How long should I wash the prints after the fixer? 6.) Is a rinsing agent like PermaWash essential to the developing process? What about a drying agent like Photo-Flo? 7.) Do all reels hold the same amount of film, or do some hold less or more than others? 8.) How much does a changing bag typically cost? 9.) If the enlarger does not say the aperture numbers on it, is there another way to tell which aperture you're using? 10.) Besides using toner or lith negs, are there any tricks or interesting procedures anyone can explain to me? 11.) Do film and paper need to be squeeged before they're hung to dry? So yeah, if anyone knows the answers to any of these questions, it would make my life a lot happier. Thank you.