CRFI
Medium Salsa,
I do not have the benefit of the CARS or the CFS here but part 1 of your problem looks right. Theoretically you need to have the minimum CRFI value for the aircraft to hold the centerline when the crosswind component is determined. These values are conservative.
Part 2 is a little more interesting. I see that you are using a PA-31 as an example, which in Canada is a CAR 703 (Air Taxi) aircraft. Under these restrictions, there is no requirement to factor your landing distance to 70%, that will be for large turboprops. Your only requirement on a dry day, barring any special considerations or waivers, is to adjust landing weight to allow a landing within 100% of the landing distance under environmental conditions. (credit shall be given for no more than 50 % of headwind and no less than 150% of tailwind, possibly idle power from 50 ft at threshold and 3 degree descent?) Ignore 60% and 70% factors.
Contamination complicates this only a bit further. I assume from aircraft type and lack of CRFI you are operating into a gravel strip in the north. I believe you are using CRFI equivalence values for loose or compacted snow, these are also conservative. You need to apply your coefficient to your normal landing distance like you did and read the corrected distance. This is factoring once. If you were limited by a 70% factor on dry pavement you would need to ensure your weight satisfied the more restrictive of contamination penalties and 70% penalties, but not both at the same time, that would be double factoring. If large aeroplanes were limited by double factoring, they would never fly in the winter in the north.
To sum up a TC guy that I trust, use AFM charts for dispatch limitaions, (in your case unfactored) and use CRFI charts while airborne using the latest info not available at dispatch time and apply them to unfactored landing distances to avoid double factoring. It may be unclear in the CFS but this was the intent of the tables.
One last comment, depending where you fly, the penalties may still be prohibitive without doubl factoring. My advise? Never underestimate the grip that snow covered gravel has on tires. It's far better than snow covered pavement and the crosswind is less than advertised due to shelter from the trees.