After revision for a hanging columella and tip refinement, how long can I expect swelling to last? (photos)

Overall the shape of your nose is fine other than the hanging columella, but would benefit from tip refinement.   Swelling after revision takes at least as long to resolve as a primary rhinoplasty.  You have relatively thick skin which is contributing to the lack of definition of the tip, and swelling is as well.  Precise dissection with meticulous removal of scar tissue, and monthly steroid injections usually yields improvement and resolution of most of the swelling within 3 months, but full resolution can take longer than a year.  The best approach is preservation of most your cartilage with refinements to reshape and thorough scar removal, and some thinning of the overlying subcutaneous fatty tissue.

From these photos, you still have substantial cartilage in the tip, cartilage that needs to be re-positioned and re-sized to create a better-proportioned tip and nose. The operation will be more complicated, especially in the tip area, than your primary.
But swelling isn't the important thing. The important thing is what your nose looks like when the swelling has resolved.
I don't really call what you have a "hanging columella." I just call it a tip that still sits too low. The entire tip sits low, not just the columella portion of the tip.
I'd love for you to see some excellent professionally-designed morphs of what could possibly be done with your nose. Morphs could also help you identify what's bothering you, and help you set a goal for the rhinoplasty that's accurate for your tastes. 
Remember that rhinoplasty is an exquisitely difficult operation to get right, and you should only have surgery if you are able to make yourself very confident in your surgeon's skills. The changes that your nose needs require advanced techniques, requiring skill that most plastic surgeons don't possess with expertise. For most noses, it's much better to not have surgery than to have inexpertly-performed surgery. Read my essay on how to stay out of trouble while selecting a rhinoplasty surgeon. And for those who have had previous surgery, it also discusses how to tell whether your first surgeon should be performing your revision.
Your nose is also a perfect example of why computer imaging is mandatory in rhinoplasty. You need to know exactly what the surgeon is planning to accomplish -- what features he thinks he can change, and by how much he thinks he can change them. I always email morphs to my online rhinoplasty consultations. When you see the surgeon's goals in the morphs, you'll know whether he has an eye for an attractive nose, and whether he shares your opinion of what constitutes an attractive nose. You'll also know whether the changes he proposes are large enough to be meaningful to you, and whether he understands your wishes enough to address all of your priorities. How would you ever get that figured out without the morphs?

The swelling can easily last up to a year. Using tape and splints after surgery will help. Also avoid exercise, alcohol, sun and take arnica and bromelain to help the recovery. RegardsDr. J