How Can I Help Reduce Columella & Tip Swelling Post Rhinoplasty?

It takes 6-12 months for the swelling to go down and doing the things you mentioned will make little difference. Only time--be patient and the swelling will go away.

In most cases, there is not much that will reduce swelling other than patience and more time. Keeping the head elevated may help with swelling somewhat, but for mild swelling a month or two after surgery, this is going to make a minimal amount of difference. Keep in mind that the nose can take a full year to see the final results after a rhinoplasty.
Be sure to discuss any post-surgical concerns with your surgeon. 
All the best,

It’s not unusual for patients undergoing rhinoplasty to have
prolonged swelling.Several factors,
including the use of open rhinoplasty, fracture of the nasal bones, thickness
of the nasal skin, and a previous rhinoplasty have been associated with
lengthened swelling.Most
patients will note significant swelling for about two weeks following
surgery.After two weeks, most patients
are comfortable resuming their normal lives and going out in public.Swelling
will persist in most patients for at least one year following surgery with the
nasal tip being the last site to experience resolution.In the immediate post-operative period, nasal
splints, elevation of the head, low salt diet, ice and rarely steroids can be
used to minimize swelling.