1) Rifles are a poor choice for home defense. Rifles are build for long range and high penetration. In home defense, the longest range is generally 40', with most engagements under 20'. Rifles will shoot though many walls and often exit a house.
That said, if you can only get one gun and you want a fun target weapon that you can also use for home defense an AR Carbine is a very good choice.
Another alternative would be a lever action carbine in a pistol caliber - such as a .357 levergun.
A better solution would be an AR-15 (or AR-10) or bolt-action target rifle and a pump-action shotgun (as suggested above) The prior makes a better target get and is fun to shoot while the latter makes a better home defense gun when loaded with #4, #1 or 00 Buckshot with more energy and less penetration.