Bill:
The beavertail is just to prevent the slide from cutting the shooter's hand during firing. (Some of the older Walthers were notorious for "biting the hands that fed them.") As for the two external safeties on your Kimber, until they are disengaged, the thumb safety blocks movement of the slide and the sear while the grip safety blocks movement of the trigger. The combination of the two combined with the internal safety mechanisms (disconnector, hammer safety stop, inertia firing pin, and integral firing pin block) makes for an extremely safe and reliable weapon.
Some 1911-type pistols, such as the Browning HP and the Colt Mustang, do not have grip safeties. While some people carry such weapons "cocked and locked," I personally choose not to do so. For me, a grip safety is essential for carrying a single-action pistol in Condition One. It's just the way I was trained by a grizzled old sergeant many years ago.