T-Max, if I recall, is intended for single use. T-Max RS is a replenishable developer and can be re-used. Kodak's info sheet provides details on this.(posted 8429 days ago)Any fixer can be used more than once.
Developer can safely be put down the drain. Fixer contains silver, a metal contaminant and should not be put down the drain in some areas. It depends where your drain water goes. I live in the San Francisco bay area, and waste water ends up in the bay. Fixer is not permitted, but our county hazardous waste recylcing facility accepts it. Check with your county or city hazardous waste department for information.
Fixer can be put down the drain if the silver is removed, but this involves some equipment and may not be worth the cost or trouble unless you use lots of it.