I searched for an hour and couldn't find a pic showing power steering fluid leaking from the hole on the back/bottom of a power steering pump. On my Legacy it appears to be puddling on top of the block just behind and below the pump where the hole is. Is that a relief passage that allows fluid to escape when a seal fails internally?

It's probably tHe o-ring that is on the bottom of the reservoir

EZ to fix, o-ring available from dealer. Can't remember exactly how to replace the o-ring, but it is intuitive, once you see the size of the o-ring. The Subie counter parts guy will show you how, and where to install.