Higher province number moves first?

[thejeff]

Movement between friendly provinces is handled first. That is known, well observed and even documented in the turn sequence section in the manual.

From my simplified debug example, it seems pretty clear that individual commanders are handled separately, whether they are selected together or not. The multiple army thing is probably a statistical artifact. Chasing armies simply doesn't work, unless he stops or turns back and attacks where you are coming from.

The sequence in the debug log seems clear. All movement orders are processed, then checked to see if any are interrupted by attacks coming the other way. Exactly what determines that is unknown.