its nvidia cards ONLY when it comes to free fps ( max 144hz/fps ).
amd cards it works but g-sync will not work in it since its dedicated to nvidia.
so if you get limited to 60 or 120 or 144 as max i can not say.

and free sync is just stil at the test and failure state as of now -> http://www.anandtech.com/show/8129/computex-2014-amd-demonstrates-first-freesync-monitor-prototype

No. No monitor is yet VESA 1.2a compliant. You very likely won't see any before 2015.

Nvidia has yet to commit to FreeSync in drivers also.