RE: .243 for whitetails
243s are great coyote/deer guns. I currently have 3 of them! LOL I just picked up my third one this afternoon. They are very accurate, mild to no recoil, and fairly cheap to shoot for the non-handloader. For deer I use the 95gr Combined Technology BTs and have harvested deer and droped them in their tracks past 300 yards. I've actually only had one deer move after I shot it (and I've shot upwards of 50-60 deer with a 243). I used to use a 30-06, then I bought a 7mag that I used for years, then I started using my 243 because it was lighter to carry (western hunting), and ever since then that has been my go-to deer rifle. It kills just as well as the bigger cartridges with half the recoil. For coyotes check out the Sierra 60gr HPs, they are fur friendly (as long as you miss the shoulder blades).