Covered another rule and learned some more from last Fri 3k battle.
Dangerous Terrain 40k6 pg 90
Once a model has taken a Dangerous Terrain test for a particular area of terrain, it does not test for that area of terrain again in the same phase. However, if the model moves into a different area of dangerous terrain, these must be tested for as normal.
Context: In the 3k battle last Fri Harlequins moved from one Dangerous Terrain to another. They had to test once for leaving the Dangerous Terrain they started in and again for entering a different Dangerous Terrain.
Walkers Overwatch 40k6 pg 84
Unlike other vehicles, Walkers can fire Overatch
Context: During the same battle it was wondered if walker (corrected thanks to Timothy Hamel) can perform Overwatch.
Placing Disembarking Models 40k6 pg 79
The models can then make a normal move -- Difficult and Dangerous Terrain tests should be taken as normal [sic].
Context: During the same battle after the Plague Marine Rhino's moved the Plague Marine's disembarked into Orikan's Temporal Snares and C'tan's Writhing Worldscape tripping Dangerous Terrain tests