Questions about size of needle for ear body face

This would largely be up to the discretion and preference of the practitioner and what you are treating on the patient and your overall treatment goals. Generally the needles for auricular treatments are shorter because they stay in better - the diameter is a preference overall. The face you could use intradermal needles for things like cosmetic acupuncture, for example, and regular body needles of nearly any length and diameter depending on the point and the clinical reasoning for using the points.

The ear can also use intradermal needles, press tacks, ear seeds, etc.

Generally you would choose based on what you are treating in the patient, the age and overall health of the patient, your preferences and your style of needle manipulation, among other factors.