Damn.
That's a lotta alloy!
Taking this; if you have 34 grooves the same TYP distance apart, you'd need 34 different distances; not an average.
I'd imagine the same would apply here; use the correct value. Worst case scenario, you know that's not the problem
Well, the various nickel and nickel alloys range from 1.5-9.8x10^-6 in/in/F, so probably not. Most of them are in the 9 range, with the special ones, like Invar, in the 1 range.
That means anywhere between .0000015 and .0000098 inches change per inch of length per degree of temperature variation.
So, .000225 to .00147 at 10 degrees and 15 inches. (If it's not Invar, it's likely to be more towards the high side.)
It's for a given distance. If you are measuring a diameter you use the full diameter size. If it is a distance between two features you use that full dimension.