The Crew is a very heavy game on the CPU and as your CPU only has four cores, i suspect this could be the reason for the fluctuating FPS.
75c is a perfectly normal temperature for the GPU. If you want a lower temperature i would recommend increasing the fan speed via Radeon Settings or using MSI Afterburner to create a custom fan profile.
I doubt it's the CPU problem when the game is loading it isn't on full load.
I also use MSI to monitor the temps and loads.