It depends... It is developmentally normal for teenagers to have anxiety, sometimes pronounced about establishing their identity and life goals. It is not normal for this anxiety to be an ongoing, incapacitating problem. If this adolescent is struggling as a result of the anxiety, he may be a good candidate for therapy like cbt or medications like ssris.
Yes it's atypical. Even if there are only thoughts about dying. The teen sounds like a very thoughtful and caring person, but if these thoughts are distressing or frequently keeping the child from doing other normal activities, it is probably best they speak with a trained therapist to help them understand why they are having these thoughts.
No. It would not be an unusual sort of thing to worry about. Having said that, panic attacks are not healthy, see your physician to get a referral to a mental health professional to get some help.