1.> The problem being that not all of them can use magic. Tt would make perfect sense for them to integrate what magic they have access to into their tactics, however. Hit-and-Run archery from behind illusion cover, magically trying to douse your light sources without generating darkness they can't see thru, ambush parties hiding in rope trick spaces, and gunning for enemy spellcasters as a top priority. Things like that would all fit, but not every one of them will have several levels in wizard. If they had the men to spare, you'd probably see something along the lines of an assigned spellcaster per squad.
2.> I can't really say that I've seen alot of fanatic loyalty in the drow as they're presented. Well... other than fanatic loyalty to their own personal wellfare. As for their slaves; their slaves don't love the drow. The drow don't do anything to inspire love or loyalty in their slaves; their slaves fear them, and have been broken by them. The typical drow-slave mentality would run something like: There's nowhere to go. You can't escape. Anger them and they'll make you wish you'd just commited suicide instead.
3.> Yep. The drow are really more of Lloth's favourite plaything, then her chosen people. She doesn't -care- for them, she just doesn't like it much when other people touch her stuff.
4.> Totally agree with you on the devious bit - "fair" shouldn't be in a drow's vocabulary. What we would see as dirty and underhanded, they see as slick and practical. The use of innate abilities.... that could go either way. The abilities are really one-shot per day, and an individual drow might want to keep it in reserve as an ace-in-the-hole should he need it to cover his own arse. The sleep poison thing... eeh... on important missions and the like, sure, but the stuff has to come from somewhere. There can't just be an endless supply of it.
5.> Ferocity is what slaves are for. If you're being ferocious, you're not thinking properly, and if you're not thinking properly, you're not paying attention, and if you're not paying attention, you're dead. I could more easily see a drow force trying to goad an enemy into getting worked up by commiting some atrocities and letting them be known. Then once the enemy is in a frenzy throw a screen of slaves at them, let the slaves draw the enemy's ire, and then move in from another angle to ream the opponent while their discipline is waning.
6.> Small but important distinction: the drow's own life above all else. As far as the drow are concerned, there's only one number that's important, and that's Number One. What was the quote about a drow army? "You'll likely never see a more formidible group of individual warriors." Discipline and teamwork for them are like the doily under a cake: sure, it's pretty and all, but you certainly don't -need- it.
^_^