Red 6,
Just to add to George's post, we have two Captains in the Squadron in additon to the OC (a major), whereas US companies have the XO. The more junior of the two captains is the Battle Captain (BC) while the more senior is the Squadron 2IC. In general, the BC looks after operations, training and fighting effectiveness (maintenance) while the 2IC deals with administration and CSS. There can also be an LO (a Lt) although he is normally only found in Recce Sqn these days if at all.
The BC acts as the link to Regimental or Battle Group HQ (battalion equivalent), much like the XO in US organizations. He passes SITREPs to higher and generally speaks for the OC on higher nets, freeing the OC to focus on the Sqn command net. That being said, the OC also monitors the higher net and will talk on that net as appropriate. In a tank squadron he does it from a tank and he is usually moving either with the OC or with the rear-most Troop. He usually commands the firebase. In a reconnaissance squadron he does this from a command post along with the Ops WO as George mentioned (two CPs by doctrine and an RRB). The Recce Sqn works for Brigade and is a callsign on the brigade command net. The Recce Sqn SHQ can function as an alternate Brigade CP if disaster strikes.
The Sqn 2IC is a more senior Captain, and he was usually the BC for the previous year and may be Kingston-qualified. In garrison he looks after paperwork for the OC. In the field he commands the Sqn A2 echelon. Our armoured squadrons are suppposed to have an A1 and A2 echelon. The SSM commands the A1 echelon. The two echelons are pretty much matched sets in that they have the same number of POL and Ammo resupply vehicles (M548s in the good old days/ HLVWs these days). They both have maintainers, although the A1 echelon has the Maint Sgt and the ARV. They each have an armoured ambulance. The A1 echelon resupplies the F echelon and the A2 resupplies the A1. The A2 shuttles between the B echelon (fairly well back) and the A1 echelon. The 2IC attends CSS coord conferences at HQ Sqn and links up with Transport Troop resupply convoys. The Sqn thus carries two days of supplies, which is handy when you have to work for some other organization who is not set-up to resupply tanks. Having all the techs in the Sqn echelon is also handy when you go to work for some other organization (although SPSS will often still be a problem). Both the tank squadrons and recce squadrons have these echelons. The recce sqn is supposed to be resupplied by the Service Battalion, but this sometimes falls to the sqn's parent armoured regiment.
There is also a B echelon which consists of the SQ and his shop. The SQ is a senior WO and he looks after stores (including the vehicles and kit). The OC might be charge but the SQ owns the squadron! If the troops in the field need stuff like consumables or clothing he is the one that looks after that.
A full-up tank or recce sqn is a big beast that is fairly self-contained.