1) To me, three to five days is an acceptable ageing time before packaging/freezing/canning. Longer is better, I've aged venison and pork for as long as 15 to 18 days. Most say that's way too long, but the beef/pork etc. that is sold at the grocery was aged thirty days before the USDA inspector would let it be processed at the packing plant.
2) I have no experience in city.
3) That silver skin can be a pain, but I don't know of any tricks. I generally try to fillet it off, just like fish skin.
Good Luck and Hope I helped a little!