stereo size

Yes, actually Subaru uses an ISO-DIN mounting so be sure the unit you buy is compatible with that. The ISO-DIN system does not use the metal sleeve as the standard DIN does, and there is no extra mounting hardware required- the factory unit is removed from the existing brackets and the new unit is attached to the same brackets. Most currently available aftermarket units are universal and will work with either standard or ISO-DIN, for the ISO mounting there may be a trim ring around the front panel that has to be removed so it will fit.

Boy, not sure how I'd do that. Here's the product I'm thinking about:

TIA, David

That unit should fit. Most of the major manufacturers are ok for the ISO-DIN install. According to your link the actual supplier would be Crutchfield, when you buy from them they supply full installation instructions along with the adapter harness (which you will need) and free tech support. You might want to contact them ahead of time to ask any questions-