I am under 30 and have the worst baggy puffy dark circles under my eyes. Would a lower blepharoplasty help?

Puffy Eyelid Bags. Lower eyelid blepharoplasty is still the treatment of choice for lower eyelid bags (fat). Unless the dark circles are a result of shadowing from the puffy lower lids, they will not go away with blepharoplasty. It is not unusual to consider lower bleph in your young adult life as the problem is typically hereditary and shows up earlier in life. Good news is that it is very rare to need it again.
Perhaps. Most younger people with lower eyelid bags do not have strong cheekbones, making the problem worse. Fillers along the "tear trough" area can help, as can a permanent implant to augment the cheeks and lower bony rim of the eyelid. Eyelid surgery in this group of people can be considered, but you'll need to discuss the pro's and con's with your surgeon first.
Yes! Reduction of excess skin and bulging fat pads often contribute to the appearance of dark circles under the eyes. It provides a "shading" of light when the bulges get large. Occasionally patients will have actual pigmentation which is dark and contributes to the problem. Large veins near the surface also may contribute to that appearance. All tend to improve with lower blepharoplasty.
Blepharoplasty. A lower lid blepharoplasty. An improve the "puffiness" of the lower lid by removal of herniated fat. There may be some improvement of the dark circles but all is not eliminated by the procedure.
It depends. There are many causes of dark under-eye circles. If it is truly due to fat bags, lower lid blepharoplasty with fat excision and/or repositioning can help. See an oculoplastic surgeon for an evaluation.
Yes. The bagginess of the lower lids can be corrected with bkepharoplasty. Dark circles could be a simple shadow effect and those resolve with the bag removal. If darkness is due to pigmentation, then the surgery would correct the baggs but not the color, nevertheless, they would look much better at your age.
Yes! Start by making sure the puffiness is not due to seasonal allergies and the general inflammation that this can cause. Once this has been ruled out, then you can consider a surgical treatment. Your eyes are likely the result of the genetic lottery and as such can make you a surgical candidate earlier than you might expect. In today's world, a good first impression is priceless!
Yes it could. It is possible that you could derive vendor for surgery but this requires an accurate diagnosis of what is causing the problem which can only be deteined at the time of consultation.
Probably. But you may have to adjust expectations and / or add other procedures.