Okay, I'll give some update and a little clarification.

The rumors I gave were based off of an early version of the rulebook. I gave it a quick read-through, so I can clarify as far as how some of these rules work (i.e., I didn't just talk to a guy who told me how it would work in bullet-point fashion). I haven't had a chance to re-read it yet, as I've been too busy with work and other things to devote any time to 40K in the last few days, so certain things I'm not really sure about until I get a chance to look at the thing again.

It was an early draft, this much was obvious by sections that had old versions of charts in them (with things like "we need to update this graph" written in on top of them). Not all the rules were complete. There were a few sentence fragments and blank places where certain rules had obviously not been finished. There was also no artwork, just large blank spaces saying "put artwork here" (basically).

So, basically going off of memory, this is what I remember (not saying that other questions can't be answered, just that I didn't see or don't remember what that answer is).

Vehicles: Fire everything if you stay still (except Ordnance, it's got special rules, and I don't use Ordnance, so I didn't look closely). Fast vehicles can fire everything if they move up to 6". If you move, you can fire 1 plus defensive weapons. Fast vehicles can move up to 12" and fire 1 plus defensive. If you move more than 6", you only fire defensive (I think you can still fire defensive weapons here, but I'm not 100% on that). Fast vehicles can move up to 18" (their max speed now) and only fire defensive. Vehicles can only fire at one target. I did not see any special rules for sponsons firing at multiple targets. Not saying they won't be in the final version, or even that they aren't in the one I saw, just that I didn't see them.

Wound allocation before armor saves: Didn't see it. It may or may not be. I was looking at other sections and really didn't expect to see any changes here, so I glanced over that part and didn't look too closely. I'll try and update later on in the week, once I see it again.

Vehicle damage chart: It's about halfway between the glancing and penetrating charts of today (1-2 is the can't shoot/move thing, 3 is weapon, 4 is immobilized, 5-6 destroyed/annihilated). Glance is a -2. If you are glanced, your vehicle can at most be immobilized. Vehicles are a bit more survivable because of the way damage stacks. If you get two immobilized results, it becomes weapon destroyed. You aren't destroyed by "cumulative results" until you've been immobilized and all your weapons are gone (and then you get one more).

Transports: If your transport is destroyed, passengers now take a Str 4 hit, saves allowed (instead of a 4+). If an open-topped transport is destroyed, it's a Str 3 hit because its easier to disembark.

Plasma/frag: I don't know about their armor penetration against vehicles. I think they're the same now, but don't quote me on that.

Assaulting in cover: If you assault someone in cover, and you don't have grenades, you now become initiative 1 (instead of them becoming init 10). This works a lot better when more than two units are in combat.

LOS: I'm pretty sure that it's units that block LOS, so you shouldn't worry about spending 45 minutes drawing LOS from each individual trooper to each individual target. You draw LOS from the eyes of the model. Area terrain gives cover saves. There's an entire chapter on ruined buildings and how they affect line of sight (like a mini Cities of Death). I honestly don't remember if 6" of terrain blocks sight or not.

Blast weapons: I didn't see anything in the rules about rolling to hit at all, just scatter. But honestly, I was on the phone with a guy relating all the stuff to him, and I can't always do two things at once. So it might be there -- I didn't get to give this stuff my complete and full attention.

Running can be done w/in 12" of an enemy. You just can't charge if you run.

More rumors:

After shooting and wounding, you can choose to become pinned. You get a +1 to cover save (or a 6+ if you're in the open). It's the "get down!" rule.

If you are charged while broken, you make another fall back move immediately. If you don't get away (i.e., they can still reach you), you're destroyed. If you do get away, umm, you get away.

Gets Hot! is back to the 3rd ed version. So that Ork character doesn't have to worry about rolling 3s on his plasma gun.

There is not a new HTH chart. Sadly, the Avatar still only hits Fire Warriors on a 3+.

Preferred Enemy now allows you to reroll all misses, instead of hitting on a 3+.

Ground vehicles that move at full speed and cross dangerous terrain roll 2D6 for their test. If one "one" is rolled, they're immobilized. If two "ones" are rolled, the vehicle flips over and is considered destroyed. Kinda cool, I think, because it represents what you see in action movies.

Flamers: You now determine wounds for all template weapons firing from a squad before you take saves or remove casualties!!!

Bikes all now get a 3+ cover save for their turbo-boost. So the psy-cannon thing is out the window.

A unit with Scouts that is inside a vehicle confers that ability to the vehicle!!! Let the Pathfinders and Possessed Marines rule!

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Honestly, one thing I noticed is that the new rules should make Dark Reapers turn back into their tank-murdering selves (at least the Exarch). An Exarch with Crack Shot and an Eldar Missile Launcher could deny a skimmer any real protection. No cover save, ka-blam!

Overall, if something remained the same, I didn't mention it. So while I understand the desire for defensive weapons to be something different than they were in 4th...