These are rumors, so please take them with a grain of salt.
Hull points don’t work as rumoured: they are only for front armour 14 vehicles and work like a structure point or a “wound” which can be used to negate any result, even wrecked or explodes. not sure if this is a once per game thing, i suspect so. but no more one shotting land raiders and monoliths with meltaguns
and pens give +1 to all subsequent damage rolls in that shooting phase, so essentially after a pen all weapons shooting a vehicle become AP1
rapid fire: double tap up to 24” if stationary. 1 shot at 24 or 2 shots at 12 if moving. Relentless gives and extra shot at each range if stationary as well as the standard bonus.
power weapons are ap3 but give a 5++ parry save in combat
Stunned results stack to weapon destroyed, extra armour negates 1 stun per turn, not sure on shaken
Strength vs toughness chart changed to be like fantasy, so everything can be wounded on a 6.
there's going to be a bunch of FAQ/erratas when it drops for all codices
vehicles being hit in combat is auto if stationary, 3+ is going 6", 5+ if going 12", 6+ if going flat out
though, vehicles going flat out can only be hit on a max of 4+ with shooting, fliers hit on 6+
Damage results stack so shaken -> stun -> weapon -> immob -> wreck
Preferred enemy gives re-rolls to hit with shooting and in combat, but not the re-rolling of 1s to wound