"Line of Sight in 40k 6th Ed." Topic

I've been reading through the little rulebook that came in the Dark Vengeance starter (got it last summer, but haven't really done anything with it till now!) and I want to make sure I have the LoS rules correct. I haven't played 40k since 3rd edition, when LoS was a 90-degree arc to the figure's front. From reading the 6th edition rules, it seems infantry figures no long have a set facing or arc, and can shoot in any direction provided you can draw a clear line to some part of the target model's body (not weapons or equipment etc). Is this right, or have I got it all wrong?

Also, I notice vehicles still have a facing, as do walkers. For walkers in H2H combat, you always strike at their front armour, but do you have to actually turn the model when it is attacked, or can you keep it's current facing and still count as front armour?

Finally, is there any major rules errata/updates for 6th edition I should be aware of?

No you do not need to turn the Walker to face the enemy.

Yes, LoS is to the target's body but this would be as if he was standing normally.

So I was reading it right that there is no arc, infantry can fire 360-degrees?

yes, 360.