Can an infection from a wisdom tooth cause neck swelling and swelling behind the ear plus swelling under the wisdom tooth/jaw? I have no pain with it.

See oral surgeon. Soft tissue swelling in the head and neck region can become dangerous if pressure is placed on your airway. Regardless of the cause, seek treatment at once.
Not usually . Most dental infections have dental pain, painful swelling, fever so unlikely. I would be concerned about something going on in the parotid salivary gland which is in the same location you're describing. See ent.