Considering a few things: chin implant or jaw advancement, dorsal hump removal, & forehead augmentation. Any suggestion?

Having a front and head tilted back views of your face would have helped me to advise you more meaningfully. However, based on the posted views you are a good candidate for rhinoplasty and chin advancement. Without the benefit of examining your occlusion it is impossible to recommend to you or dissuade you from undergoing a jaw surgery. However, based on the profile pictures it seems that the difference between the aesthetic gain from the chin surgery with or without jaw surgery is going to be unsubstantial and jaw surgery may not yield enough aesthetic improvement to be worthwhile since often you have to have orthodontic work before jaw surgery while that is not necessary for the chin surgery. As to the forehead, I would be in a better position to advise you if I could  examine you in person but it does not seem that a major forehead advancement is going to be worthwhile. We have less invasive procedure available for the forehead contouring, if necessary. You are correct, inability to breath through the nose results in certain changes in the face and chin which those of us who have craniofacial training (specialized training on the facial surgery) deal with them routinely. Correction of your breathing will need to be an integral part of your surgery. At your age we prefer sliding osteotomy over an implant, without a strong feeling, since it is more physiologic, more powerful and more versatile than placing an implant. 

Your nose would benefit grom a simple basic rhinoplasty to flatten the profile and other minor retouches.The chin is short and this deserves chin enlargement. Being an option, chin implants have serious disadvantages, specially in
the mid and long term, patients are rarely happy with them after 5-6
years, all are out by then or later.Consider the chin advancement by means of sliding genioplasty, the advantages are:-lifetime procedure, no more revision or renewal procedures-more natural than implants-no visibility of implant edges during gestures-improves
the double chin effect at the sub-mental muscles (floor of mouth)
hammock caused by lack of tension there; also improves the shape and
tension of perioral muscles; implants do no offer this feature-horse-shoe enhancement, covering the chin and also the jaw sides of it-no future displacements or neuritis of mental nerves-practically zero infections and 100% healing of bones-no
need for complex plates and screws that may need future removal; just
steel wires synthesis may suffice, they stay buried into bone callusThe cons are:-expensive, but cheap if you consider the lifetime pros-technically
demanding, few surgeons are experienced or comfortable (though I
personally perform 100% of the chin augmentations by this osseous
method, always after offering the patients both options)-scary for the patient (though not so much if you explain well the stuff around it)You'll
find in this website dozens of negative experiences with chin implants
in the short and mid term, do read my profile's Q&A and you'll find
them too. I am doing sliding genioplaties for 15 years with the highest
success and no one patient regreted, totall the opposite, I did many
chin implant removals and one staged sliding genioplasties to replace
them.

 The combination of a rhinoplasty and chin implant is very commonly performed in our practice. A closed rhinoplasty approach can address decreasing the projection of the nose, removal of the dorsal hump, and refining the bridge line and the tip accordingly. A chin implant can be inserted through submental approach to give augmentation to the chin to help with facial balance and proportions. Chin implants are manufactured in a variety of sizes and shapes, are composed of Silastic, and can be placed at the same time as the rhinoplasty, or as a stand-alone procedure. For many examples of this combination, please see the video and the link below