1---"i havent been able to feel my legs or walk far for almost a year now. would gan green have set in yet?"
Gangrene results from "complete" blockage of the flow of fresh oxygenated blood to an area of the body e.g. your legs. Since your arteriogram showed complete blockage of arterial blood flow to your abdomen and lower extremities and you presently have symptoms of ischemia in your lower extremities ("havent been able to feel my legs or walk far for almost a year now") then you will progress to gangrene. This will depend upon the amount of collateral circulation that you have remaining in your legs; however, with an arteriogram showing complete occlusion, you have no collateral circulation which means you will begin to show signs of gangrene within a few months (if not already). Progressive gangrene, rapidly enlarging wounds or continuous ischemic rest pain signify a threat to the limb and suggest the need for revascularization. Bypass grafts are usually required because of the multilevel and distal nature of the arterial narrowing in critical limb ischemia. Patients with diabetes are more likely than other patients to have distal disease that is less amenable to bypass grafting.
Heparin assists antithrombin III and prevents conversion of fibrinogen to fibrin. Heparin does not actively lyse a clot but it is able to inhibit further development of thrombi (clots).
#2---"if they do the bypass is there a chance i could lose my leg(s)?"
All surgery carries risks. If you have complete occlusion of your arteries then you have more of a chance of losing your legs if you don't have surgery then if they do the bypass. There is less chance of side effects following surgery for revascularization than with amputation. Limb preservation should be your goal.
Hidradenitis suppurativa is caused by follicular occlusion which, in turn, occludes your apocrine (sweat) glands and causes perifolliculitis. Treatment of hidradenitis suppurativa includes incision and drainage of the growths followed by antibiotics. Long-term administration of erythromycin and tetracycline has been used to treat the chronic stages and is shown to reduce the relapse rate. I recommend that you be treated with appropriate antibiotic therapy prior to and following your surgery to prevent problems associated with your hidradenitis suppurativa.
#3---"what are my chances?"
Based upon what you have written related to your condition, your chances for improving the quality of your life by having the bypass surgery far outweigh the chances of you suffering side effects during or following the surgery. You should ask how many bypass surgeries your surgeon(s) have performed? The more surgeries that your surgeon has performed, then, obviously, the more skill he has developed and this will usually predict a more successful surgical outcome.
You should always get a second opinion (in person) whenever a physician suggests surgery.