Remmington 870, Mossberg 500, Winchester Super X series, Benelli M4 just to name a few that i would recommend as Home Defense, but if you want overkill, i would go with a Saiga 12 gauge loaded with 000 buck.

I'd probably be fine with either but I prefer my weapons accurate and semi-auto so a light rifle would be good. Probably won't use a scope unless it's an ACOG/dot sight. I'm not afraid of iron sights and I love using them as long as they are done well like in Crysis 2. Secondary would be whatever is close to a magnum/machine pistol.

I never liked the SMG in FPS games, since it's more about spamming and aiming too long at the target.
A Sniper rifle and a pistol did good in every FPS game I've played so far, since my aim is good and sniping is too much fun.