Mandrakes
The first is Mandrakes. A unit you really do not see on the tabletop, however I have been working on ideas on using them. I think tactically there are times to use this unit. However my first impression would be to wait now a bit, as every other marine player you face now is Grey Knights. Yes, mandrakes now count as daemons.
While I find it a little odd, since there is nothing under unit type saying daemon (its a new codex after all), this change wont effect too many people, except that they will look even less at the poor Mandrake. Its a codex change, and a nerf for a unit that already has very few reasons to be on the tabletop.
Snikrot
Just say wow. Another great FAQ ruling in favor of Orks. It seems that if you are going to play a xenos race, play the one that the faq writers also play. (joking of course). Snikrot can now bring in other Independent characters from the players board edge. How fun this is going to be. Remember your Independent character coming with him cannot leave the unit until the following round after he arrives. But fun.
Kustom Force Fields
I am not going to get into a rule debate on this one. Its very cut and dry. Now you simply have to put two of your three cans within 6". Pretty simple. A lot of arguements going on with this one.