The FAQs:
http://www.games-workshop.com/MEDIA_CustomProductCatalog/m1830600a_40k_Rulebook_version_1_3.pdf
http://www.games-workshop.com/MEDIA_CustomProductCatalog/m1830601a_Grey_Knights_v1_0.pdf
Here are some things that stuck out:
Q: If a Grand Master gives a unit with personal
teleporters the Scouts special rule, can they use the
shunt move as a part of their Scouts move? (p22)
A: No.
No more first turn charges!
Q: Does a Dreadknight with a Nemesis doomfist strike
at Strength 6 or Strength 10 in close combat? (p34)
A: Strength 6, as it is not a walker.
Awkward wording on the NDF, but I guess that makes sense. Makes the Great Sword something to be desired now over what we thought was S10.
Q: For each Jokaero Weaponsmith in a henchman unit
after the first you add +1 to the Inconceivable
Customisation roll. Does this mean that if you have 6 or
more Jokaero in a unit that they will receive no
bonuses (as you cannot roll less than a 6 and duplicate
rolls are ignored)? (p50)
A: Yes.
So I guess take 5?
Q: Can models in Terminator armour embark onto an
Inquisitorial Chimera? (p51)
A: Yes.
And here's the final word.
Q: If a model with a Nemsesis force halberd has had his
Initiative reduced to a fixed number by an
ability/special rule, do they still get the +2 Initiative
from the Halberd? (p54)
A: No.
Lash Whips rejoice!
Q: How do you work out whether a psyker is affected
by the Psi-shock special rule on a mindstrike missile or
a psyk-out bomb? (57, 58)
A: Any psyker under the template will be effected by
Psi-shock.
Been playing it like this for a while, but I'm glad they made it clear.
Q: Do you take into account the strength increase from
the psybolt and psyflame ammunition vehicle upgrades
when working out if a weapon is a defensive weapon
or not? If a vehicle has either of these upgrades, must
you use them? (p62)
A: Yes to both questions.
S5 Hurricane Bolters do not count as defensive weapons! I hope everyone's been playing them right.
Q: Would an orbital strike relay targeted within 12" of
one or more servo-skulls have its scatter distance
reduced? (p62)
A: No, it always scatters the full 2D6".
Just icing on the cake.
Q: Are Wounds from Dangerous Terrain tests allocated
in the same way as shooting attacks? (p14)
A: No. Each model moving through dangerous terrain
must take a test. Each model that fails takes a Wound
A lot of people have been playing this as shooting for the purposes of allocation, but I'm glad that it's clear as day that each model has to take DTs. This increases the chance your IC, Sanguinary Priest or Meltagun dudes fall on their face when jumping.
Q: Do the effects of the same psychic power cast
multiple times on the same unit stack? (p50)
A: Yes, unless specifically stated otherwise.
This is big, because this means that Hammerhand from a Librarian can stack with Hammerhand from a Paladin squad. If you have a Grand Master in there, you can test for HH 3 times, so on and so forth. Interesting...
Q: Can a psyker attempt to cast the same psychic
power more than once in a turn? (p50)
A: No, unless the psychic power itself specifically allows
it.
This means that you can't just bring a Libby and have him spam HH to buff your dudes. In order for you to stack, you must cast from separate sources.