Hey Al! Standard advice in the industry would be to point you towards the 100mm brakes. Are you measuring them when they're deployed or retracted? That'll make a big difference in terms of clearance. Most brakes build in a few millimeters of wiggle room so you could theoretically get away with a 90mm brake on a 95mm ski, though with these ones the 90mm is definitely a proper 90mm brake.
Hey Tim! It's possible it'd work though we don't have a Soul 7 here to try it with so I definitely can't say yes or no with confidence. At the moment though it looks like I only have one 100mm brake in stock.
Hey Lyman! At 5' 6" you could definitely go either way depending on your usage intention. If it's strictly going to be for ripping groomer laps in the resort and then venturing off-piste as well, the 171cm would be a pretty easy choice. Though for a steep ski or mountaineering ski with some use in the resort as well, the 164 is the sensible choice and would still do really well in the resort though you may sacrifice just a touch of high speed stability. For reference, I am ~5'7" and ski the 164 Voile Object...
Hey Tim! Your guess is as good as ours, the pivots on the X-Alp/Proclines haven't been made available as a spare part so who knows if these will work or not. The safe bet is that no, they won't work.
Hey Evan! Potentially! There are about 5 bindings that have the designation "FT 12" so it's important to know which generation of binding you are aiming for. The "classic" toe pieces are the 5-Hole patterns like the Vertical, Comfort, TLT Speed, etc. The hole pattern on Dynafit heel pieces hasn't changed much up until just recently, but you definitely can't mount the heels to the fast plate though as those are designed for the Kreuzspitze heels.