Both of the shotguns I will recommend would not be the best for hunting, but since home defense takes priority over hunting, I will recommend them anyway....the Tactical Response 870 or Mossberg 590 with ghost ring sights. Both of these seem to work well (my preference with the TR-870)and the ghost ring sights get you on target fast and work well with slugs also if they are needed.
For ammo, my pick would be Federal's Tactical low recoil 00 buckshot and perhaps some low recoil slugs from the same company in a side saddle. Both are available from ammoman as well as J&G Sales.
I'm not a fan of birdshot size loads for self defense because most do not penetrate deep enough to provide reliable stopping power. A load of #6 shot will create a nasty wound, but most of the shots will probably not penetrate deeper than 4". The low recoil buckshot penetrates well and still has plenty of power. Plus the recoil is tame enough to allow for very rapid follow-up shots. These pellets may actually penetrate deeper than they would from a max dram load because the pellets suffer less deformation and therefore penetrate deeper. If you are worried about overpenetration, use a load of birdshot as your first round or two, but back it up with buckshot if these fail to stop the threat. Hope this was helpful.