Wow, lots of questions. Let me take these one at a time.
First of all, I will admit, we should've waited an extra two or three months and released a book that could do everything. In fact, hopefully by February or March we
will be releasing the accessory book that
can do everything.
To Anon Dragon
A 'disintegration' effect is one of those things we forgot to add in. Mild mistake there; we double-checked to have lots of different elements, but we didn't always make sure to have opposing elements to everything. As a quick fix, I'd suggest 'Void' could equal disintegration.
To Victim
Another error. I'd have to check with CZ for the exact answer, but I think it just denies them their Dex bonus to AC.
Regarding Alter Reality, yes, I don't have my copy available right now (replying from work), but if you're right, then yes, it should say Alter Reality 6.
For abjure elements, it wouldn't be too hard to provide an option based on total amount resisted, instead of amount per round. I'd say something like 10 points at 1st level, 30 at 2nd, 60 at 3rd, 100 at 4th, 150 at 5th, and so on. That's, what, an arithmetic sequence? Algebraic sequence? *grin*
I don't quite see your point about having to change creatures. What do you mean?
Also, I don't have my copy available, so I don't quite know what you mean about the concentration DC. I'll check when I get back home.
Combination effects will be in the accessory book. If you've ever played the RPG Talislanta, they sidestep the problem of this complexity by saying that "ancient magic was able to combine different effects, but such knowledge has been lost, and current magic is limited to only single effects at a time."
To Volcivar
We did not actively choose not to include haste. Rather, we didn't have any time-based stuff in the book, and of the various spells seen in fantasy, speedy ones aren't the most common, so we kept it out in favor of other, more common types of magic.
However, we did consciously remove the restriction that you have to have an Intelligence score of 10 + spell level to cast spells of a particular level. If you want, you could play something of an idiot savant, with great magical powers but little brains, insight, or personality. So limiting spells per day of a given spell level by ability score could result in a character unable to use magic at all.

However, since the system is meant to be flexible, if you want your setting to have spellcasters that are intelligent because that fits your setting's feel, then by all means, go for it.
Alternately, you could just say that no more than 1/2 of a characters MP can be used for a single spell level. Or perhaps say that a single spell list can be used no more than once per level per day (with a possible explanation that the spirits of magic grow angry if they are called upon too often).
I personally don't think you need to limit it, since even if you do cast 10 9th level spells to kill a demi-god dragon, you'll be out of luck when the dragon's kobold henchmen starts chasing after you with a pointy stick.

If you want to add restrictions, I'd say to do them for flavor reasons, not balance.
To Phaedrus
I think letting people spontaneously cast a single spell would not be overpowering at all.
To animate dead, take Infuse Creature with Death, then Animate Object. If you want permanent undead, either go the mythical route and just have corpses be animated by uneasy spirits (without needing a mage to cast spells), or have a spellcaster Craft Wondrous Item to make a 'Corpse of Animating.'

Note that this would technically make the creature a construct, but calling it undead for the purposes of 'Abjure Undead' would be perfectly fair. This is one thing that I do wish we had done more work on, since undead are pretty staple creatures.
Regarding outsider immunities, follow the guidelines in Abjure Element to have them have 1/2 resistance to related elements. Anyway, it's no fun fighting a monster that is totally immune to your magical attacks. Creatures should have elemental resistances for flavor reasons (a fire demon being immune to fire), but not just to make life difficult for adventurers.
To R-Kelleg
A multiclassed paladin white mage is very possible. You add their caster levels together. For purposes of spell lists they can learn, whenever they take a level of a particular class, they can only choose spell lists from that class. However, they can cast any spell list they know. So a paladin 10/white mage 1 could choose Evoke Area Force, something a paladin could not take. She could cast it just the same as any other spell, since the MP pool is shared between all spellcasting classes.
The Medium saving throw was first introduced in the Star Wars D20 version. I don't see why it'd be a problem.
Having divination spells be skills reflects that a lot of spellcasters in fantasy literature seem to have sort of a 'magic sense,' without having to cast spells.
And now I'm off work, so I must go.