Yes, it is. I've run Office 2007 on the 32-bit and 64-bit Release Candidate versions of Windows 7, on the official Release versions, and on the Service Pack 1 upgrades. No problems in any of those cases.
Its 100% compatible.
Yes it is. I am running Office 2007 Professional under Win 7 Pro. There are a few glitches when you use Excel but they can be worked around - usually. Word-processing is not aproblem
Sorry by Glitches with Excel I am presuming you may have work done on older versions of Office.