Tactics Questions - Line and Column, Stacked or Not Stacked

[pokeytrev]

Hello, 
As some of you may have already read, I am new to the Napoleonic system. I had a couple of things that are bothering me that I feel like I can get answers to on this forum. Questions are bolded while any quotes are italicized. Thanks in advance!

In the user manual, the following paragraph threw me for a loop:
"Line formation is most effective defensively while Column formation is
best for attacks. In Line formation, your infantry will have its greatest
firepower. You should use firepower to cause Disorder and casualties in
attacking forces so as to reduce their ability to attack you. In Column
formation, your infantry is easier to control and will suffer less Disorder."

Is it always better to keep your soldiers in column if you are attacking? I had always thought it would be advantageous to move into position and switch to line to increase firepower for a better chance of dislodging the enemy.

Next, I noticed that line infantry will often time start out stacked upon firing up a scenario. Does stacking further reinforce and increase your fire output, or would it be better to simply unstack units and extend the line/create reserves? I don't think that one of the stacked units can fire based on something I read in the user manual. It seems like stacking line infantry doesn't have any tangible effect?