Apple's touting the iPad Pro as a full PC replacement. That might be true for anyone who's really mobile, but if access to legacy apps and corporate systems like Active Directory are important, it might not fit the bill.
Your Mac and OS X have a variety of startup keys and key combinations you can use to affect how the device starts up. Shift key, for instance, starts your Mac in Safe mode, and C (or c) starts up from a bootable CD, DVD, or thumb drive. Command-S is for