you can start reading this sire for an in depth overview ( yes I know)
napoleonic-literature.com
then skirmish games, suffer from the lack of dismount red cavalry figures, then if using cavalry lack of space.
Do use many more figures, it looks better and allows for freak dice results that won't kill the game, especially if you have several players.
Use Sharp practice from the 2fatlardies, with house rules to fit your game.
No, if you have two patrols / small groups, unless a band of deserters ( as in one of the Sharpes) they will 99% of the time be from the same outfit/company; this is not hollywood.
patrols:
for reconnaissance; capturing prisoners for questioning; infiltration / Getting in a secret agent.
very common; missions for foraging. One side or both; could even be three competing armies ( allies?)
You can blur the picture if you have several players with assigning different objectives (secretly or not) even personal disliking between leaders
White knight and dark bad guys, on same side? one normal mission and some in the outfit or another band on loot and rape. Probably very common too.
securing a bridge.
ambush /petite guerre on wagons. again if there is a box of cash
.
raids and landings. destroying depots./ fortification /bridge.
Lasalle going behind Austrian "lines" to spend the night with one of his conquest. He speaks German and makes her believe he is Austrian ally. (authentic)Things get a bit edgy next day to come back, meeting real Austrians with escort and other help
Prisoners escape.
In houses/ houses block fighting in Saragossa.
Sieges; night sorties on trenches/batteries.