What are good levels of HDL cholesterol?

Higher the better. Epidemiologically, the higher the hdl-c, the better, with notably reduced risk with hdl-c in excess of 60 mg/dl. The problem is that this is often genetically and gender dependent, & there is scant evidence that raising hdl-c per se (independent of triglycerides and ldl-c) by drugs will change clinical outcomes. We have new agents in trials that significantly raise hdl-c & may improve outcomes.
Varies. For men, we recommend a level > 40 mg/dl, for women, it's > 50 mg/dl.