Testosterone level (total) 282.73 ng/dl. Is this considered low or normal?

Generally low. If this is a morning blood draw, it is generally low and may need replacement. Make sure to check more than once before deciding. Also check free testosterone, lh, fsh and prolactin. Discuss w/your doctor.
Reference range. Always ask your doc for reference for your results. Different labs use different techniques to measure same thing. Reference range may also vary depending upon gender & age. Most labs will label total t >250ng/dl as normal (altho some might not) in a young male. But more important than number is how you feel. Why was test ordered? We're here to treat patients, not numbers. http://goo.gl/d4hpo.