My guess as far as Shara is that D basically had to level the place to gain full control.  Yes, they started with a lot of channellers, but most of them were not DF; and when it comes down to it, most people are willing to fight and die rather than side with the DO.  Along with normal sectionalism, I can see that he really needs to kill lots of people to solidify his rule.

2. One possible advantage I see to individuals channelling is that it creates a lot more weaves heading towards the enemy at one time. More weaves than one person can deal with, as the human brain can only process so much information at once.

You're right; the light just needs to send three channellers with an escort, maybe 200 people tops, and Caemlyn is gone.  Elane was already willing to burn the city to the ground to get the trollocs out, so this isn't any different, and no one has to fight.

I disagree that they felt the number of trollocs was infinite.  It was clearly stated in multiple places that the dark had nearly emptied the waste of shadowspawn in order to conduct the invasion.  While the light was outnumbered maybe 20:1 in total numbers of bodies, the number of shadowspawn they needed to destroy was not infinite.  With what should have been an advantage of 3:1 or so in channellers (WO + WF + AS + Kin + AM + SD = many thousands), that was the light's ace in the hole. 

The logical thing to do would be to have Rand (because Egwene and Logain probably couldn't agree on which of them should do it) lead a full circle w/ everyone using the strongest sa'angreal/angreals available, and nuke Caemlyn.  Don't balefire it, just nuke it.  Poof, one army gone.

This will probably draw out Damendred, and Rand would be anticipating this.  A plan would need to be in place to deal with him.  But if he doesn't come out, simply rinse and repeat.  The light really did have all of the advantages here, and they threw them all away.  But, it is a theme of the series that people do really stupid things and don't see obvious solutions, so I'll go with it.  It was a good read.

This would be a good thing to ask during Q&A.

I agree that the Light's strategy was very bad.  From their perspective the situation was thus:  The enemy had divided their forces into three.  You have interior lines, plus instantaneous travel.  Your enemy cannot use instantaneous travel, and must rather walk.  You're willing to go full on Stalin with a scorched earth policy.  Therefore the light can easily create overwhelming superiority on any one front, and defeat the dark in detail.

The light clearly should have formed up all of their military power at one point, and gone and defeated each army in succession.  Victory would have been nearly assured, rather than a close run thing, and losses, while still severe, would have been much less.  Mat should have been in charge from the beginning. :)