1. Company CO and lance leaders have C3 Computers. The fourth Master's location does not matter
2. Each Lance/Platoon has is a cohesive network (contains 1 or more Mechs with a Master), but the rank does not matter of the assignemnt.
3. All units with a Master are technically assigned to one particular lance, and the network is within the company, but there is no relationship between Master/Slaves and the unit organization.
4. The company has a flexible organization. There's assignment to a standard lance/platoon, and a combat lance/platoon, but the units mounting C3 Masters can have any rank of unit commander.
None of the above.
I very rarely run an entire company.
As it is, far more often I will have a single Lance network spread throughout the company, so that 2 members are in HQ Lance, 1 in Battle, & 1 in Striker, etc etc.
That said, when I am designing a full company I almost never use a double master.
And while the "Officers" could be the mech w/ the C3M they are not guaranteed to be so.
The 2nd Master will be in the Command lance almost always simply due to logistics & that more Master units are big & heavy.
Heck, prior to the Jihad it was hard to even find a unit that moved 5/8+ that mounted a Master for your Striker type lance leaders to use.
Due to that little issue, I have designed some networks where all 4 Masters are assigned to the Command Lance but they network out to the Lower Lances.
For example
CO = Cyclops-11C = Company Network CM
XO = Atlas-CM = Lance Leaders Network
Command Lance #3 = Avatar-C = 2nd Lance "Non-Officers" Network CM
Command Lance #4 = Avatar-C = 3rd Lance "Non-Officers" Network CM
Battle Lance = Victor-C, GrassHopper-C, Quickdraw-C, Kintaro-C
Recon Lance = 2x Firestarter-B's & 2x Owens
The above formation isn't listed in Total Warfare as a "canon" option but there is nothing particularly illegal other than the C3 Network "Members" are not the same as the "Lance TO&E" arrangement. It is nothing more than a "Variant" of a canon formation that changes the TO&E locations.
When I am running a C3 company pre-Jihad, that has proper lance configurations, I almost always end up with a few custom Mech/Omnimech variants to make the unit work.
I usually use a BlackHawk-KU or Firestarter-O with a variant pod load for the Light lance C3M since there are no C3M's for either omni in the 3050's era.
Medium lance is a bit easier, you could use a custom Blackhawk again but can also find GrandDragon or Avatar versions w/ a C3M.
Heavy/Assault lance models I use most often are Cyclops-11C, Atlas-CM, Gunslinger-2ERD, or several different Heavy/Assault Omni's with Custom/Canon Pods.
Those are just the C3Ms but you end up a bit short of C3S units too depending on the "role" you are looking for & the year your playing in.