Are you sure you need a shotgun? One thing is that a long gun in a house presents some greater rentention hazards than a pistol.
If you do, you'll be able to run an 870 just fine. Trigger finger runs the slidebar release, disengage the safety before completely grabbing the comb, or if it's already pointing at something you don't like just snake your trigger finger around the trigger and push the safety off with it. Reloads from a sidesaddle are pretty quick too, I can chamber load, (AKA combat load) pretty fast. With the shells pointing up I just rip one and loop it over the top of the reciever with my stronghand, don't dismount or unpoint the gun. Reloading the tube is best left for when you have a little time or cover, preferably both. I guess I don't need to point out that if you're reloading an 8 shot 870 in your house you're already having a pretty bad day, may want to consider a different zip code.