Slitherine

1. When you need to retire to 3MU from shooting, the rules seem a bit vague whether this is 3MU from the firers or from all enemy?
2. When skirmishers or artillery retire as an outcome move through friends, do the friends need to take a CT, or does this only apply when being burst through?
3. Do irreg cav need to take a test to charge limbered artillery?

1. When you need to retire to 3MU from shooting, the rules seem a bit vague whether this is 3MU from the firers or from all enemy?

I believe it is from all enemy, so 3 MU from the nearest enemy unit, not necessarily the one that shot at you.

2. When skirmishers or artillery retire as an outcome move through friends, do the friends need to take a CT, or does this only apply when being burst through?

Skirmishers can not pass through friends so it is a burst through. Unlimbered artillery abandon guns and run to nearest unit, no effect, limbered artillery would burst through I believe.

3. Do irreg cav need to take a test to charge limbered artillery?

I don't think so, technically limbered artillery really does not count as a combat unit. The limbered guns will make an evade move before the cav begins their charge.

To confirm:

1) 3MU from ALL enemy.
2) ANY unit passed ( or burst) through by friends making an OUTCOME MOVE (regardless of type or formation) will need to take a CT
3) Limbered artillery can be charged by skirmishers without taking a test. (treat limbered artillery as skirmishers for this situation). I'll add a clarification of this next time I publish an update.