1) DeTrobriand is marked on the counter as entering at 15H. The setup for the Day Two Scenario shows 16H. Is this a typo or is there another scenario that uses the 15H on the counter?
16H for the Day Two scenario but use 15H for the Gettysburg Campaign scenario.
2) Why is the To Hit hex terrain base chance for the town 6? I would think it would be harder to hit in town.
In Civil War games, I have seen it go both ways but in more current games, towns are often considered death traps.
I point you to this article, specifically to the 3rd and 4th paragraphs:
3) The rules state approach fires are "resolved simultaneously",
I interpreted the "simultaneously" to be part of the following sentence:
"All Approach Fires are resolved simultaneously during the Combat
Turn. The order in which fires are resolved does not matter."
In other words, they all happen at once - the outcome of one does not effect the outcome of another. In other words, if moving enemy unit A is shattered by Approach Fire by friendly unit B, friendly unit C would still have to fire some of its strength points at enemy unit A if applicable (See page 19 of Special Rules and imagine that CSA Wright was also marked with Approach Fire to understand what I am talking about...)
I hope that helps.