Yeah don't go PowerPC whatever you do, almost nothing supports that architecture now. You should be ok though, I think they made the Intel switch in like 05/06 so you shouldn't really be looking at 6 year old Macs anyway.
Naivety it is not. Hardcore OSX users are really just hardcore Unix users. OSX is just sporting a custom GUI on a tweaked version of FreeBSD that will only run on specially coded hardware (as in DRM). That's why a hackintosh is so hard to build. There's nothing truly special about Apple products other than the ability of…