How worried should I be with total cholesterol 280, 30 yr old female. Just started pravastin. Seems to be hereditary, is it meds forever?

Moderately. It would definitely be wise to make it part of your lifestyle to lower/keep low your cholesterol to a reasonable degree. You are young, and this could effect your future life. Medication is likely to be important, and prevastin, a statin is a strong drug that can have side effects, like muscle pain that needs medical attention. Diet control and exercise is also important now and in the future.
Depends. Depending on just which kind of problem you have inherited, and where your weight and diet are now, you may be able to get off medications with exercise & diet. Even if the genetics are against you, diet and exercise will decrease the amount of medication you will need to control your levels. If you can hack it, a vegan diet may be for you. Good luck!