Its how benchmarks work. The demo is actually a set of frames that need to be played. It benchmarks your system by calculating how long it takes to show all those frames. The better your system the faster your fps and the quicker it shows all those frames.
Its the same with futuremark benchmarks and if anyone has doom 3 or even quake 3, running a timedemo of a demo will do the same thing.
The final game wont be like this, this is just for benchmarking purposes.
No, it's not.
The reason is purely because of the underlying engine specific to SFIV. The physics engine and frame data runs at a strict 60fps, hence scaling up the frame rate scales up the physics.