Mesh Outfreakage and weight map issues

I've been thru this once before and then again recently, so here is the drill for my own reference and anyone else who might find this useful.

DO NOT SCALE BONES
Alter rest length to adjust bone length/size. Otherwise you will distort your mesh unpredictably.

To fix, revert scale to 1 in all 3 axis, and multiply the REST LENGTH by the inverse of the former scale to get the length you want.

Tiny bones and weight map issues:
I found tiny bones would drive weight maps fine, but other nearby bones seemed to effect the edges of that weightmapped area, as if the tiny bone could not maintain influence over its whole weightmap and was overridden by movement of the bigger bone nearby. Adjust rest length to something more in proportion and problem fixed. (We are talking about a bone which had been about a tenth or hundredth the size of the other bone.