Why does a tank platoon cost the same in size modifiers as an infantry company? I would think the tankers could be ready faster than the infantry.

The reason for this seeming incongruity is that abstracted into this size differential is the maintenance and logistical considerations of the tankers. The tanks need to re-arm and refuel frequently. Instead of burdening the player with these details the game does them for you whenever tankers are "between missions. "

An infantry platoon is destroyed via the Fire Combat Table or through SYR disintegration. In which case is a +2 added to the company morale, or both?

Only infantry platoons destroyed due to Fire Combat Results on the Fire Combat Table add the +2. SYR losses, AT Rolls, Artillery/ Mortar vs Point Target Tables do not add this, ever.

A stack of six units is moving along and triggers overwatch fires. How many times do we roll to determine permission, etc.?

Only once. Basically you are overloading the defender's with targets. They cannot fire, observe and adjust fast enough to engage more than a few of the herd of tanks to their front before the targets disappear.

When calculating the modifierfor the morale check from the Fire Combat Table, is the "total steps lost" referring to the platoon checking morale or the entire company?

The steps the unit checking counts, not the whole company.

What mode is a suppressed or paralyzed unit considered to be infor Terrain Effects when fired upon?

It is still considered to be in the mode it was in under the suppressed/paralyzed marker. The idea is that the troops are now pinned down where they were and are still as protected or exposed as they were before being fired upon. If in move mode, this means the troops are prone, under fire, in the open or whereever else they landed when they hit the dirt. They are just as protected or unprotected as they were when they started because they can't move to change the situation quickly.

If a carrier is destroyed using Area Fire, do the passengers still get the bonus to their defense?

No. When the carrier is destroyed, it is removed from the map and the troops are considered to have dismounted.

An infantry unit can make as many AT Rolls as it wants during the Suppressive Fire Phase. Can more than one AT Roll be made against a given target if more than one "firer" is available?

No. Only one such roll per target, per phase is allowed.

Is it within the spirit of the command rules to allow a unit conduct a diversionary attack away from the main objective?

Sure. As long as it is recorded on the op sheet as such. In fact a slick plan would be to take a round-about route, launch a diversionary attack, then move on the real objective all as part of the same operation. Such plans tend to work particularly well against players who try to react to everything.

Must a player identify the exact observer at the time of writing up an artillery fire mission?

No. But once the mission starts, he should identify the unit taking responsibility for firing the mission and from that point on, only that unit can observe and adjust fires.