Essential Terms in a Valid Contract and the duty owed by physican because of medical malpractice

Question

1.    In order for there to be a valid contract there must be  on all essential terms.
2.    In medical malpractice actions, the duty owed by a physician arises from the  .

Summary

These questions belong to Law and they are short questions which require precise answers. The first question is about what constitutes a valid contract on all essential terms. And the second question is about medical malpractice, the physician owes responsibility to the patient.