What width skins?

You want to go for the widest point on your ski and trim down from there - so typically your skis should be wider than the nose width of the ski. If you have really fat or rockered skis then you can trim a taper into the tip and tail, but you definitely want the skins close to the edges of the ski.

I haven't had experience with narrow skins, but I'd predict you will get decreased sidehilling and turning hold. You might not notice much of a difference going straight though.

so you figure i should have gone with 115mm width? Perhaps i should return these puppies and see if i can snag 115mm width ones? Or does it really have that big an impact? I could survive with 100mm but would be ideal with 115?

108mm waist skis.

i think you'll be fine. you generally want 2mm on either side on your skin to make sure to accomodate for your edge. enjoy!

the only other thing i have noticed is that there is about a foot on the tail of the ski that is somewhat poor coverage of the skin on the ski because the ski is slightly short and maxed out towards the top of the range. 178cm ski with a ski that claims to be meant for up to 181. Its not terrible coverage but still a little bit worrying.

Neither, you should have gotten the 125mm skins.

I bought the 140mm skins for my Caylors (148-120-140). Although you could get by just fine with the 115mm skins, optimally you want to trim off of most of the length of the ski to get the skins to fit the best.

But the 100mm skins are definitely too skinny either way.