"For a double chin, InMode FaceTite with VASERlipo would give you the best result.
With significant neck sagging you would need a facelift / neck lift with muscle tightening (platysmaplasty). At the same time, I would recommend lasers (Fraxel, CO2, Halo, or Erbium) and microneedling RF...
Regarding neck, your result may be too early and will improve in time; a small amount of Botox into visible msucle bands may help. Regarding nostril asymmetry and columella issue, very likely that you would need some sort of cartilage grafts by means of columella strut or extension and...