[Soyweiser]

Well it is actually pretty complex. Here are my experiences with turn orders.

Ordering a commander to go into hiding after he has not been in hiding. This includes sneak. The changing of the status of the commander is the first that processes. So, the next turn the commander will count as hiding for target purposes. (Not 100% sure if this applies if you sneak). Note: Move/attack resolution happens later. I would also assume that if you change your orders to move, you count as not hiding from the start of the turn.

Attacking a province you are currently standing in. Happens in the magic phase if the province is targeted by magical combat spells, move phase otherwise. (I have had stationary scouts take over provinces that where targeted by anonymous attack spells, conventional wisdom told me the scout would attack in the move phase. It didn't (also, he went first. So I didn't take that province)). Other magical attack spells (cloud trapeze, summon ghouls) cause your sneaking unit to join in the attack.

I don't know what happens if you cast a anonymous magic phase attack spell and you move+attack with a sneaker into that provice. But I assume the same happens as a normal magic phase attack spell. Aka, sneaker attacks in move phase.