"Questions about Bonnie Blue Flag ACW wargames rules" Topic

Hi,
I recently bought the Bonnie Blue Flag ACW wargames rules by Kevin Calder (published by Partizan Press) and there are some areas of the rules I'd like clarified please.
On p 17 for movement it says to roll a d6 and add the appropriate movement for the unit type.
Does a unit have to move its full distance or can it choose to move up to that distance? E.g. if an infantry unit rolled 4 on the d6 does it have to move the full 10 inches or can it move less, up to 10 inches?
For mounted cavalry the move is 12 inches plus 2 d6 if charging. Does this mean that charging cavalry go 12 inches plus 3d6
How do units turn when moving, by wheeling, or pivoting or something else ?
Can units move oblquely if moving straight ahead, and if they can move obliquely to what angle of straight ahead?
If units can change direction how many changes of direction can they make in a move and when can they make them?
In the Under Fire Results table on p 22 what is the definition of infantry advancing? Is it only infantry which was moved by the player with initiative being fired on by the non initiative player during that turn or does it also refer to infantry moved by the non initiative player in the previous turn being fired on by the player with initiative in the current turn?
In the meleee modifiers on p 26 for "Having a supporting unit in melee" how is this defined? What is classified as a supporting unit?
Many thanks and all the best,
George.