Are palpitations deadly?

Not usually. Palpitations can be sensing a norma heart beat in some patients. Most do have abnormal rate or rhythm. Most often premature contractions are noted. These are absolutely benign. Rarely, more worrisome rhythms can be seen. These need to be ruled out in someone with palpitations.
Almost never. It is normal to have up to five "skipped beats" / "flipflop heartbeats" per minute, especially if you like to drink coffee. If they occur in a run, or if they take your breath away or cause actual pain, a physician's office visit is in order.
Maybe. Palpitation means a sensation in the chest of irregular heart beat. Usually these are benign. It may be an irregular heart beat. It may be just a sensation of of your breathing. Check your pulse to see if the heart is irregular. If you are worried, get it checked.
No. Palpitations are usually not deadly and are more just an uncomfortable feeling. With that being said, some palpitations can lead to fatal heart rhythms. If it is bothering you that much, I would put a holter monitor on you to determine the underlying morphology of your EKG. If that is concerning, it would be best to start some medications.