I see a lot movies where they show troops lining up just standing their waiting to be shot at, than the next line shoots at the enemy. They show often that canon balls explode and grenades, and that to fire a musket, you had to look away from it. Are any of these true? Did cannon balls really explode? Did you actually have to look away from the musket while aiming?
While you wait for more targeted answers, you might be interested in some threads from the FAQ section on "Line Formations aka Linear/Napoleonic Tactics":
Why did European armies use Linear Tactics?
Did Line Infantry really march into enemy fire at a dignified pace before attacking? (As is portrayed in many films set in the 1750-1812 period) - 27 comments, over 2 months old.
The commenters list cavalry, organization, and inaccurate weapons as the primary factors and also link to a variety of posts on the topic.
Napoleonic Battlefield Tactics - 5 comments, over 11 months old.
The commenters here summarize the threat of cavalry charges to open order infantry, the morale damage caused by massed volley fire, and the training requirements for large groups of sharpshooting skirmishers.
Was the colonial tactic of "stand in a line and shoot" really the best tactic for war, or the product of not knowing how to best use guns? - 26 comments, over 9 months old.
The topmost comment addresses the problems that line formations solved while top level comments below it put it in context with early modern firearm development and also the noise and smoke of the period battles.
Please help me make sense of how infantry battles were fought in 18th century Europe. - 6 comments, over 1 year old.
This summarizes how line infantry actually conducted themselves once in range of opposing formations.
Were battles during the time of the american revolution truly fought with two lines of armies standing across from each other with each army taking turns firing at the other? - 40 comments, over 8 months old.
This thread touches on the threat of cavalry, range limitations, and how period line infantry fit into the whole of contemporary armies filled with skirmishers, cavalry, and artillery.
When was the first instance of a bunch of guys with muskets lining up in a line and firing at each other in volleys? - 12 comments, over 11 months old.
The commenters here summarize the evolution of European firearm tactics European from 15th to the 17th centuries.
Why did armies in the 18th and 19th centuries face each other through lined combat? - 1 comment, over 4 months old.
The lone comment gives a summary of line infantry tactics and also discusses how these soldiers would be used in various phases of the battle with links to other posts on the topic.
18th-century battle formations - 24 comments, over 7 months old.
The topmost comment discusses the use of line and column formations while a top level comment down below it digs deep into how line formations interacted with skirmishers and cavalry to show the importance of closed order units.
Did armys really just stand in line and shoot at each other back in the 1700's? - 21 comments, over 10 months old.
This thread both explains the theory behind the tactic and uses a variety of examples from Early Modern european battles to showcase the mechanics which allowed it to be effective.
Would line infantry keep a musket loaded for when they charged, so they could use it at extremely close range? - 6 comments, over 1 year old.
The commenters in this thread discuss why and how bayonet charges were conducted.
In "What was warfare actually like in the 18th/Early 19th centuries?", a user makes a relevant comment here - 5 comments, over 2 years old.
This posts discusses in detail the tactics and strategy of period sieges, cavalry, light infantry, and artillery to show how line infantry filled a crucial role in 18th and 19th century warfare.
What books (websites?) describe the military maneuvers used during battles of the 18th-19th century? - 5 comments, over 1 year old.
A variety of sources are given by flaired users.
Artillery, skirmishing, and aiming
When units of ranged troops fired en masse, did individual soldiers pick their targets or fire straight forward/at an area? - 41 comments, over 9 months old.
The commenters in this thread give detailed answers for British forces during the Revolutionary War as well as 18th century Russian soldiers.
In 18th century Europe, how was artillery deployed offensively during battle? - 7 comments, over 6 months old.
Various flaired users discuss the types of artillery and their roles in European battlefields from the 17th century into the early 19th.
American Revolution: When the red coats intially saw the hiding tactics of the americans, was it seen as constoversial as current day "terrorist" tactics? - 3 comments, over 1 month old.
A flaired user gives a detailed post (with primary source evidence) showing the tactics and formations used by British infantry during the American Revolutionary War.