I have been deer hunting with a shotgun in Ohio for 20 years. If you want to shoot a slug for Home Defense or really at anything within 50 yards shoot a rifled slug (the cheap ones, remington, winchester, federal, brenneke, whatever). You can shoot this out of your regular barrel with no mods...something other than just a front bead is useful.
If shooting a regular old rifled slug any choke other than full is fine.
If your shooting at distances of closer to 100 yards+ get a rifled barrel and shoot sabots (the expensive ones, remington copper solids, winchester partition gold, winchester platinum tips, etc). A scope really helps out at these distances too. Dont shoot a rifled slug through a rifled barrel...
if your going to buy a slug barrel to shoot the cheap rifled slugs through it save the $$ and get a smoothe bore with rifle sights.
Buckshot...again you dont need anything special. Any choke from mod or more open will work. However they do make specialized buck shot choke tubes. I use a Patternmaster for waterfowl hunting with large BBB shot size, and these tubes work awesome for the larger shot size. But you dont NEED it. About Patternmaster - Benelli Chokes | Beretta Chokes | Mossberg Chokes | Browning Chokes | Winchester Chokes - The Science of Shot.