I'll respond to your water temperature question. Recently I discovered that simply using warm instead of hot water when washing my hair (and skin), seems to improve its health and appearance.
Same with blow-drying it. Putting it on the warm setting, rather than hot, has created a marked improvement.
Also, when you're adding product to your hair, like conditioner, warm water is good because it opens your hair cuticles, allowing hair to better soak up the product. You can run cool or cold water over your head as a last step in your routine to help close your cuticles if you want your hair to dry with added definition and shine.