It is impossible to give you good advice based on this photo. In person consultation or, at least, series of close up photos is needed for good evaluation.
The limited photographs from the side profile demonstrate a recessive, chin and fat deposits in your neck. Placement of a small chin implant will augment your chin forward for better structural support for the soft tissues in your neck. If the fat in your neck is located above the platysma...
Yes you need to both remove excess skin via facelift and replace the volume since you loss them from your weight loss. Nowadays there are fat-like biologics from MTF you can use if you have no fat any where else. Sometime dermal fat augmentation might also helps by removing the excess skin...
