Should I get double jaw surgery + genioplasty? Am I a good candidate for genioplasty? (Photo)

The downgrading of your maxilla will of course lengthen your face exactly by the number of mm downgrafted. It is simple math. Likewise a lenghrhenig Genioplasty will do the same and will lengthen the lower 1/3 of your face from the lip commissure downward and it will stretch your skin as you asked.

Thank you for sharing the photos. You have a case of bimaxillary deficiency (more dentoalveolar rather than skeletal base) . And you are absolutely right in that you will require comprehensive treatment to achieve dramatic improvement. This is likely to be a combination of presurgical...

Yes, you certainly can. The bimaxillary osteotomies are at different units from the zygomatic complex and hence independent. It primarily depends on your surgeon and whether he is happy to do this combination . You are likely to have a longer recovery, however not significantly.