Tea infusion

Hi! I've got couple of questions. Should I use the leaves more than one time. What teas are best to use more than once? Can I use lets say Earl Gray more than once? How to store the used leaves? Do I let them dry or use them still moist? How long should I put them in water? Are the temperatures for later infusions still the same as for the first one? Non-connected question: Is tea really better without sugar? Thanks in advance!