Based on difference between codices I think... things that I think I've seen but now can't find are most likely because it's an outdated version.
1) Guardian Weapon platforms. Can they move and fire? P39 of 5th Ed Codex says a heavy weapon mounted on a weapon platform counts as an assault weapon in all respects, so it could move and fire (and if rule stayed the same into 6th ed. even do Battle Focus with it), but I can't find a corresponding snippet in the 6th Ed. codex, so is it now a heavy weapon, move or fire? (On a side note, I think it also no longer says that a grav platform is just a marker, and it has a profile with differing T and Armour Save, so believe it now takes up a space in a wave serpent whereas before it didn't?)
2) Wraithlords. 5th Ed. codex, p66, says if a 2nd weapon is chosen which is a duplicate of the first one, it counts as a single twin-linked weapon (from the heavy weapons choices, not the shrunken cats/flamers). No stipulation of this that I can see in 6th Ed. codex, so assume that it would just be 2 weapons, even if both are the same type, or is there a more general rule in the BRB that says that things having 2 identical weapons count them as twin-linked? (I've looked in the obvious places, but not found one. I just want to check that I'm doing this right). As another side note to this, assuming there is no more general rule in BRB, then if the wraithlord had two flamers, it would cause 2D3 hits firing on overwatch, rather than D3 with re-rolls to wound?