Hmm.
I’m a horrible chronovore, So I’d engineer all my cells into the immortal (benign) cancer type, which will just keep on trucking in the division/self-re-newing department… Forever. No more dying of old-age thankyou very much.
Against disease I’d re-engineer my entire body into a new and unique cell type, essentially becoming a species of one. Human diseases would have a hard time infecting me then, and little point or benefit in adapting themselves to do so.
I’d add a new photosynthetic layer to my epiderms, becoming a photovore as a back up to good-old-fashioned omnivore, covering the green with an optionally translucent layer of cuttlefish chromatophores, for the cool skin colour of choice and reactive camoflage for all the super-heroing I’m bound to do.
Gills of course, would be a must, plus the deep-diving whale’s armoured circulatory system, to counter compression. Antartic fishes’ antifreeze blood too. A camel’s ability to generate water from fat, would be handy in the desert. Also their heat-radiatory capillary system. This would of course mean painless slimming by going without water for a couple of weeks.
I’d whack a whole lot more myolin into the sheaths of my neurons, to keep my mind ticking over nicely, and develop a new organ somewhere, which produces undifferentiated stem cells, as spare parts for any degredation. I’d also cross myself with a Stegosaurus, and have a back-up brain in my lower spine, in case of a head-shot.
I’d leave the wedding tackle alone, as I’m happy with its size, but add voluntary control over errections, to circumvent viagra bills.
Semi-Consciously controlled Hypertrophic tendencies in musculature for the “gain with no pain” angle. Improvments to lung capacity, and red-blood cell counts, to go with the muscles, no point in strength without endurance.
Anti-oxidant/free radicals chemical production in all cells too.
Hmm… Since I’m in for the long haul, I’d better add the ability to secrete a diamond-hard, radiation-proof crystallis, with a solar-sail, and suspended animation. For when the sun goes red-giant.
Weapon capabilities, I’d enginner my colon to generate the chemicals required for bomb making, and shit C4. Salamander detachable/regrowable little fingers containing spooled mega-long axons and lacunae filled with organic nitro-glycerine for detonators. Electric-Eel handshakes, and cool porcupine hair.
I’d give myself claws like wolverine, for no reason other than that they are fucking cool.
SuperTab.