I concur with what RB is saying. You need to be a bit more specific on "harsh" Some say a harsh ride is driving a Porsche 911 C4 and some say it is elegant in its own right.
As for the whine... is that relative to vehicle speed or the noise is constant?
Coolant wise... stick with BMW coolant. Dealers change $20 to $25 for the liquid, but it gives you two gallons which is roughly $10 a gallon. Prestone is what $18.99 at AAP and AZ? Just spend the little extra and get the right stuff.
As for you losing coolant... you will need to do some searching. Obviously check for leaks around the expansion tank and hoses... If there is nothing you can see leaking, get under it and look by the transmission bellhousing. If you see greenish/blue crust... you very well may have a valley pan gasket leak down the middle of your motor. Which in that case, will progressively get worse as you continue to drive. If you look in the "articles" section, I made a DIY on the Valley pan gasket replacement...
Also, please put your X's info in your signature such as I and RB has. It will make it easier for people on the forum to I'd your problem better.