The first thing I would suggest is for you to be evaluated by a specialist in eyelid surgery. When you actually point out which eyelid you prefer and for what reasons, you might find that you are not really asking someone to make an almond eye into a round eye. Terms are...
I would not plan on a surgery improving your allergic response. However, If your bags are already surgical in nature, then that baseline would likely improve with surgery.
Unfortunately the allergies tend to be a separate issue and will need to be controlled medically. if...
The doctor may remove skin with ptosis repair especially if it is excessive. If the excess skin is contributing to your impaired visual field then yes it should be done.