The closest app which satisfies that list of criteria is Microsoft Windows Photo Gallery. It is a free application which supports RAW files (providing the codec is installed.) Tagging can be done by location and built in face detection. While the metadata is not stored in a separate file it uses the (formerly Adobe specific) XMP metadata system, which makes the data accessible to other applications should you wish to switch later. I've used it on well over 1TB of images.

Google Picasa is also free and does face detection and tagging. But (last time I checked) it stores the data in a proprietary data file and that database is not stored with the images (so cannot be easily exported between machines).

Adobe Lightroom (and Adobe Bridge) store their metadata in a separate XMP file for each image but don't allow for automated face detection and tagging. While definitely not free you can get a 30 day trial to see if you think it's worth the money first.

Extensis Portfolio may also suit your needs although it looks to maintain its own private database so it depends on how important that is to you.

All these applications work on the Window 7 OS (tagged in the question.) There are other systems listed in What software is focused on reviewing and organizing images? but most don't meet your criteria to the same level as the ones included here.