Yes it can join friendly units, and yes, at the end of the phase when the Necromancer is killed the Corpse Cart is moved outside the unit (remaining in base contact with it) as close as possible to the position it was occupying when ridden.

No.

The FAQ Council recommends that players follow the normal randomization rules for characters riding upon monstrous mounts against ranged attacks.

Yes.

The spell is targeted on the Corpse Cart itself. This means that it affects friendly units within 6" of the current position of the Corpse Cart and that it does effect friendly Undead units engaged in combat.

Yes, it does. It gets the bonus to its armour save, but also the Movement penalty.

As this statement is under 'Ethereal Movement', only the Movement penalty is ignored and any other effects (like damage) still apply.

If a unit using ethereal movement suffers from Stupidity, they would be affected as normal. Failing a Stupidity test requires the unit to make a compulsory move. Compulsory moves are not considered to be a movement penalty. Therefore, if an Ethereal unit fails a Stupidity test, the unit must make a compulsory move of half their base movement value straight forwards, just like any other unit.

No, the challenge simply does not happen.

Only Power Dice.

Yes.

Yes, as this is not a 'shooting attack' as such. All hits will effect the enemy unit and not any of the friendly units engaged in combat with it.

Yes.

Only one wound per casting of the spell, just like in Summon Undead Horde.

These models can be placed within 1" of enemy units their own unit is engaged with, but not within 1" of any other enemy.

Yes, per the main rules Fell Bats and Bat Swarms count as Unit Type: Infantry. In addition they are both explicitly classified as Infantry on the Vampire Counts Reference Sheet.

Spirit Hosts created via Wind of Undeath may be healed up to the starting number of wounds on their profile (i.e. 4 per base).

Yes, the spell explicitly describes its affect when cast upon a friendly unit engaged in close combat.

Yes. Refer to the answer given to Invocation of Nehek above.

They follow the rules for Raise Dead and Invocation of Nehek, so the new unit of Zombies can be created with 12", while the second effect has a range of 18" around the caster.

No, he is the exception (he is way too mad for that!)

Yes, but remember that the Sword of Waldenhof has no effect on models that only have a single wound to lose.

The power is restricted to allowing units of Crypt Ghouls (and characters which remain attached to the Crypt Ghouls) to make a march move. It does not allow a character to separate from a unit of Ghouls and make a march move.

Yes he does.

He gains an additional attack for every Wound remaining on the slain model's profile.

No, nor can he fight on foot. He must ride his Barded Nightmare.

Yes you may. The maximum unit size as printed in the army list restricts the starting size of units, not the size they may eventually become.

Yes, as casting Summon Undead Horde to increase the size of units is the same as casting multiple Invocations of Nehek.

Absolutely, and remember that once that model is killed, any extra attacks allocated against it are wasted.

No, the Unholy Lodestone only works when the spell Invocation of Nehek is cast (including Summon Undead Horde).

No, see answer above.

Only Ward and Regeneration saves are allowed. The Black Axe of Krell was errated to indicate that no armour saves are allowed against these additional wounds.

He passes his WS of 4 to the unit.

He will use the Lord's WS of 7

They will use the Lord's WS of 7. We recommend casting the spell on the Lord instead!

Absolutely yes, as fights are resolved in order.

If the wearer is not himself in base-to-base contact with the enemy, he can use the Helm of Commandment.

No, the Bloody Hauberk should be treated as a suit of armour and may not be combined with mundane heavy armour.

Yes, the -2 is in addition to all normal modifiers.

The Hand of Dust may only be used upon enemy units.

Yes.

If the bearer rolls a "1", first resolve the wound as normal (take saves, apply killing blow, etc.) and then the bearer suffers an additional wound with no armour saves allowed (Of course, if the model has already been slain, this extra wound would matter only in a challenge...). If the wound is rebounded, the victim only suffers a single wound (with no armour saves allowed), which does not carry any of the other consequences and special rules such as Killing Blow, multiple wounds, and so on.

When the Vampire is slain, the Monstrous Mount IMMEDIATELY takes the Monster Reaction test, as normal. If then, at the end of the phase, the Vampire returns to life he will be on foot and cannot remount the Monster.

Correct, the Ring would not save the Vampire, so we strongly advise against such a combination!

If the unit charged into combat in the preceding Movement phase, or earlier in the same Magic phase, they can use the benefits of Hatred and other bonuses that rely on charging (such as lances) both in the attacks during that Magic phase and in the following Close Combat phase. If the unit was already engaged in combat from a previous turn, they gain no benefits from Hatred, etc.

No, the text of the spell is very clear - its effects only apply in the following close combat phase.

There is no save of any kind against wounds caused by this item, as the Vampire is voluntarily sacrificing his life-force. It can be used any number of times per Magic phase.

Yes, that means 1 pt per model.

Yes, that means 1 pt per model.