changes from NWN to NWN2

I am looking for the "low-down" on what is changing from NWN to NWN2,
other than the whole 3.0 vs 3.5 thing and the other obvious changes
such as new character classes.

For example, one of the silent changes in the Undrentide expansion was
that the maximum ability bonus went from +10 to +12. That is, if your
dex bonus from spells and equipped items was +11, then Undrentide
would give you the full +11, whereas the original game capped it at
+10. This may sound like a minor point, but it can determine your
choices for high-end equipment.

Another change was the behavior of chain lightning. The original game
gave full damage to all monsters hit (which was incorrect, according
to the description). Undrentide fixed this (secondary targets get
half damage).

Yet another change in Undrentide was the introduction of Isaac's
Missile Storm, which was a completely hosed spell. It basically broke
mage PvP unless all parties agreed not to use it. Since each missile
individually counted against a Spell Mantle, Isaac's effectively acted
as a Spell Breach. This of course made Spell Mantle and Spell Breach
obsolete --- two key aspects of mage PvP.

If this is not already done elsewhere, I would like to start a list of
such non-obvious changes from NWN to NWN2. For example is the
double-haste bug fixed in NWN2? (Under some circumstances, if you
cast haste on yourself while hasted then you lose your haste.)

I am looking for the "low-down" on what is changing from NWN to NWN2,
other than the whole 3.0 vs 3.5 thing and the other obvious changes
such as new character classes.

For example, one of the silent changes in the Undrentide expansion was
that the maximum ability bonus went from +10 to +12. That is, if your
dex bonus from spells and equipped items was +11, then Undrentide
would give you the full +11, whereas the original game capped it at
+10. This may sound like a minor point, but it can determine your
choices for high-end equipment.

Another change was the behavior of chain lightning. The original game
gave full damage to all monsters hit (which was incorrect, according
to the description). Undrentide fixed this (secondary targets get
half damage).

Yet another change in Undrentide was the introduction of Isaac's
Missile Storm, which was a completely hosed spell. It basically broke
mage PvP unless all parties agreed not to use it. Since each missile
individually counted against a Spell Mantle, Isaac's effectively acted
as a Spell Breach. This of course made Spell Mantle and Spell Breach
obsolete --- two key aspects of mage PvP.

If this is not already done elsewhere, I would like to start a list of
such non-obvious changes from NWN to NWN2. For example is the
double-haste bug fixed in NWN2? (Under some circumstances, if you
cast haste on yourself while hasted then you lose your haste.)