As I indicated, your choice of fan is likely to be ok; don't sweat it—
— but
frankenduck often has valid workarounds that can help calm the waters concerning outcomes.
The fan will start and stop as necessary—no problem. Don't let that bother you either, that usually means the system is either working appropriately, or there's isn't enough coolant in the system. The main thing is to have clean radiator fins with relatively fresh coolant in the radiator and expansion tank, and refill the system according to BMW's instructions. I change coolant every couple of years but
long life coolant is promoted to last around five years.
The fuel tank can get hot to the touch. You can always add a fuel cooler that could decrease the fuel temperature a little. There are a few threads here concerning that. Verify you have insulation under the floor of the tank—stuff like Reflectix that can be purchased at Home Depot. There is a document concerning heat management on the site and even more threads concerning insulation to mitigate temperature swings.
MartinW, a member here that lives in a paradisical hell below the equator—has taken several successful steps to cool things down.