I spent a 31 year career in cardiac surgery, and had bypass surgery myself, so I think I can speak with some measure of credibility on the subject.  First of all no surgery is without risk, but the morbidity rate for a patient without coexisting conditions is remarkably low.  Significantly less than 1%.  With regards to quality of life after surgery, there is no reason that you can't rehab and be better than you were preop, 6 months to a year later.  If you were a belly shooter before, you can be one after.  Many patients biggest challenge is a mental one.  They see the event as a milestone in life that marks a passage into disability.  Nothing could be further from reality.  It's simply a surgical procedure (all be it a greater that average risk one) that has a recovery period that will lead back to a normal life.  It's of extreme importance that the take the cardiac rehab program seriously.  READ THAT LAST SENTENCE AGAIN, TWICE.  You get back physical ability in direct proportion to what you put into your exercise program.  With regard to bone healing of the sternum, it will be stronger after surgery than before.  It takes 4 or 5 months for the complete healing of the bone, but it will heal.
A pet peeve is the incorrect description of cardiac surgical procedures with regard to open or closed approach.  Bypass surgery IS NOT open heart surgery.  It is a surface procedure that is performed on the arteries on the surface of the heart.  Open heart cases are conducted on the inside of the heart, on the valves, or other structures IN the heart.
You should do well if you are otherwise healthy, and have a strong commitment to getting better after surgery.