TheiC - Is an ATR difficult to control when landing within limits on a contaminated runway? My experience of turbo-props is that they are the most pilot-friendly of all aircraft (ie. fixed wing; before one of our rotary friends wobbles up) when operating on slippery surfaces; but you have to respect the aircraft's limitations.
And let's return to the airport. EDDM is one of those airports that is generally open with wet runways, full width, full length BA Good or shut for snow clearance operations so they can bring it up to that standard. But if EGNV is your destination, you'll need a calendar for flight planning because snow clearance may take some time.
As for tanking values, I think common sense applies. I would also expect guidance in the form of a recommended tanking value. But I can also remember a certain captain who was so insecure they departed from virtually every airport with an additional three hours of fuel. It wasn't tanking, it was just under-confidence. But the effect of doing so often compromised that aircraft's payload on the next sector - over-tanking if you like.
PM