"Hefty" is right, there's quite some cool things in there.
For example, there's been tons of posts the likes of "I only have one resolution with the 302 driver!" on forums, the IncludeImplicitMetaModes stuff takes care of that. And being able to set UseDisplayDevice to "none" will help Bumblebee users.
I'm not seeing the 64-bit version of this.. when I navigate to the 64 bit drivers for my GPU, I only see the one that was released one month ago.
Also, I'm still waiting for a legacy driver where the installer actually works for my old GeForce 5200 FX or whatever; the driver is out, but I can't for the life of me get the installer to work-- at this point I'm fed up with and scared of .run files, so I guess I'll just wait for a .deb
Is that (DKMS) the last piece needed for Wayland compatibility, or is something still missing?
No, DKMS is a set of scripts which automatically compiles kernel modules for newly installed kernels.
KMS is something completely different. In its most basic definition (Kernel ModeSetting) it means that the video mode is controlled by code in the kernel module. The way most people refer to KMS, however, is the DRM/Gallium3D/Wayland definition that refers to a specific KMS implementation. Nvidia already has the former, but they do not (and most likely will never have) the latter.