Starcraft2 180% CPU usage?

That is more than okay, since you have 4 cores.
And 93° C is still below the 105° C Tmax (maximum CPU temperature befor automatic shutdown).

Playing a 3D game is CPU intensive, thus the CPU usage and the heat (CPU gets hot due to more power being used due to more cycles it has to run).

 

100% is just one core's maximum. If you have 4 cores (or two with Hyper-Threading), you will have 400% maximum. If you have 8 cores (or four with Hyper-Threading), you will have 800% maximum.

 

Apple calculates load a bit odd.

When windows says 20% or 100% they are talking normalized to the max load of the entire CPU.
Apple's activitiy monitor normalizes to the max load of a single thread. Which can result in a load of 380% on a dual core chip with 2 threads.