Ok, Companies are a little more complicated. First, understand that resembling a company in OFP is very difficult. However, it is possible to resemble a portion of a company. Anyhow, it is important to understand a company when making missions on a platoon level anyway.
Once again, there are 5 basic types of infantry companies: light, heavy (regular), air assault, airborne, and ranger. Each company generaly has a squad-sized command element, 3 rifle platoons, and a heavyweapons/mortar platoon. Now for some specifics:
Light infantry company
1 command section (CO HQ) - 9 men: 2 officers (CO & XO), 1 First Sergeant (1SG), 1 Fire Support Officer (FSO), 1 Communications sergeant, 1+ RATELO operators, 1 Supply Sergeant, 1 NBC NCO, 1 Armorer
3 light rifle platoons (shown in above post)
1 antiarmor section - 13 men total, not sure who or what
1 mortar section - 6 men: 1 Section Sergeant, 1 SL, 2 mortar gunners, 2 assistants
Airborne infantry company
1 CO HQ
3 airborne rifle platoons
1 mortar section
Air assault infantry company
1 CO HQ
3 air assault rifle platoons
1 heavy weapons platoon - composed of 1 mortar section and 1 antiarmor section (not sure why this is a platoon while light infantry does not. mobility issue?)
Ranger company
1 CO HQ
3 ranger platoons
1 weapons platoon - composed of: 1 platoon hq, 1 mortar section, 1 antiarmor section.
Regular infantry company
1 CO HQ
3 rifle platoons
1 mortar platoon - 1 PLT HQ, 3 mortar squads: 5 men each supporting an 81mm mortar (instead of 60mm)
7 HMMWVs
1 2.5 ton truck w/ trailer
Note: regular infantry has larger squads (11 men each), heavier mortars, a .50 MG, and its own vehicles.
Anyway, companies have about 125 men, so using them in OFP makes things difficult. As I mentioned earlier, you can use a portion of a company in your map.
For example, the CO HQ usually sets up a command post in the field (CP). In a platoon-sized map, you could have the player be a platoon leader and visit/start at the CP where he recieves his orders/gets briefed. Then, he must travel to his platoon and join his squad and start a platoon attack, following the rest of his waypoints. Through scripting, you might be able to guide the other squads and call in airstrikes/artillery. If not, the PL or PSG usually positions the 2-3 machineguns if part of the PLT HQ.
Company organization pictures:
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/7-10/ch1.htm#c1p17Battalions... I don't have much knowledge on them, but I do know that they are usually assigned an area the size of Nogova to control. Maybe the player can visit the BN HQ in a mission or something. For information on a rifle battalion:
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/7-20/toc.htm