Really irregular heartbeat, chest pains, diagnosed with wpw. How serious is it, what can she do to keep it under control without getting the surgery?

Wolf Parkinson White. This is an ekg abnormality. See a cardiologist.
Get Rx'd. Wpw is extremely serious business and this young person has every right to effective therapy. Since the 1990's, the mainstay of therapy has been radiofrequency ablation which is usually extremely successful.