You can go further these days with a Mac homie, Thunderbolt-attached, external GPU's. I use them for 3D SfM work. Of course, you can also just fire up massive GPU-servers on AWS, too.
Yes, and it's close enough for baseball. The most work is in the post-processing toolchain to compensate for the spherical aberation of the GoPro - which is hardly rectinlinear. When I use the DSLR (5D+17L T/S), it's much better, because that lens balls in terms of being much more rectilinear-like. And I have some parlor tricks.