By Gerry Shih and Bill Rigby SAN FRANCISCO (Reuters) – Microsoft Corps new Chief Executive Officer, Satya Nadella, finally unveiled Office for Apple Incs iPad in a polished debut that set him apart from his energetic predecessor while signaling his plans to make mobile apps the top priority at the worlds largest software company. At a news conference Thursday, executives demonstrated a new touch-first version of Office crafted for the iPad, available for download as a free app, though a subscription is needed to let users create or edit documents rather than just read them. Significantly, they did not demonstrate any software on Windows machines, telegraphing a departure from former Chief Executive Steve Ballmers focus on the personal computer operating software and its own devices. Their absence speaks volumes, said Daniel Ives, an analyst at FBR Capital Markets.