Will the swollen skin tag like gum above and next to my erupting wisdom tooth go down? no pain, just swelling. warm water&salt would help swelling?

Yes: Yes, it sure will and salt water rinses helpful!

Operculum: If the tag of tissue is covering the posterior part of your wisdom tooth, it is probably inflamed due to food/bacterial impaction or trauma from the maxillary tooth hitting it as you bite down. It may shrink away on its own, but in many cases a small excision does the trick. Try to clean it well and see your dentist if the problem continues. Wisdom teeth are often removed due to lack of space.

See your dentist: Sometimes wisdom teeth are valuable asset when healthy and properly aligned, but more often, they are misaligned and require removal. The removal of wisdom teeth is one of the most common procedures at ages 15-24. See your dentist for evaluation, x-rays and definitive treatment.