How are corps supose to operate in the game

[Cpl Steiner]

Fully agree with the usually but it did happen
#

Several companies or even battalions could be employed as skirmishers (tirailleurs en grande bande). The tiralleurs en grande bande acted in large numbers, stormed or defended a position, or turned the flank of the enemy. The large skirmish formations were usually supported by columns and artillery.
# In 1807 at Friedland, General Oudinot had deployed 2 full battalions as skirmishers into the Sortlack Wood.
# In 1814 at La Rothiere, four French battalions were formed in skirmish order by La Giberie to anticipate any attack which might develop in the rear of the wood. The French on occasion deployed even entire divisions [!] in skirmish formations. (Nafziger - "Imperial Bayonets" 1996 p 111)
# In 1806 at Jena, the French 16th Light Infantry advanced left in front towards the woods: its third battalion advanced en tirailleurs (in skirmish order) towards the wood, the first and second battalion, marching still in column, went past the right of the woods and deployed into line in the plain at musket range from the Prussian battery.
I was suprised it happened in 1814 thought the troops were too poorly trained

The key word here I think is "wood". In difficult terrain skirmish order might be the only practical formation to use.

[lodi57]

Good point here is the link
http://napoleonistyka.atspace.com/infantry_tactics_4.htm#_skirmishers
See if it confirms what you think
Again I was suprised that the Russians broke up Battalions for Skirmishing

When I said "I have never read", I meant in all French memoirs and officers reports I have read. So if someone is able to show me memoirs or reports that state that division was deployed in skirmish order, I will change my mind but actually I thing that it did not appeared  and that Nafziger made a mistake or misunderstood something.