If you go into OMFS you will never be bored. Even if you limit yourself to private practice wisdom teeth and implants, you will still throw down the occasional orthognathic case in the OR, deal with some benign pathology resection, administer anesthesia... theres no way you'd ever be bored.
There are (fairly rare) some oral surgeons who complete plastic surgery residencies after their OMFS residency. They get an advanced standing, similar to the approach taken by general surgeons who then match to plastic surgery. It simply is a ridiculously long time to be a resident. If your goal is to perform facial cosmetic procedures, then you just need to do the fellowship. If you want to practice the full scope of plastic surgery (burns, hand recons, boobs, butts, liposuction, free flaps...etc), then you'd have to complete a residency in plastic surgery.
There is absolutely a disadvantage to going a dental route if your goal is to be a plastic surgeon. It is far faster to do medical school, then a combined plastic surgery residency rather than dental school, oral surgery (with medical school), then plastic surgery residency.
Just a reminder. Don't confuse the word "plastics" with "cosmetic". They're completely different by definition.
EDIT: I forgot to answer your original question about if you're going about this the right way. I think you're asking some good questions, but you're early in your training so you probably can't appreciate what the right questions are to ask. I know far less about plastic surgery than I do about oral surgery. If you're worried about being bored, check out AAOMS's website for the public:
http://myoms.org