(This is actually a question concerning a non-BC game, but using the BC/OW combat rules for the most part. I can't puzzle the multiple attack rules)

Question 1:

How many attacks does the following Tyranid get?

Traits: Multiple Arms (the standard Tyranid amount of 4 arms total)

Talents: Ambidextrous, Lightning Attack

Weapons: Scything Talons, Rending Claws

Question 2:

If it has Two-Weapon Wielder, how will this change its attack options? Does it need TWW to attack with its talons and claws in the same turn (1 talon + 1 claw = 2 attacks)?

Or does TWW allow it to attack with its 2 talons + 2 claws = 4 whole attacks?

Please enlighten me, o wise ones.

In the topic "Some Rules clarifications from FFG" it states this:

For clarities sake Multiple arms appears to work like this:
Multiple Arms (3) - gain +10 to climbing/swimming, gain 1 extra attack (3/2, round down)
Multiple Arms (4) - also gain 1 extra attack, 2 total (4/2)
Multiple Arms (5) - no benefit (5/2, round down), 2 extra attacks total
Multiple Arms (6) - also gain 1 extra attack, 3 total (6/2)

Where multiple arms (3) means you have 3 arms.

In the topic "Some Rules clarifications from FFG" it states this:

For clarities sake Multiple arms appears to work like this:

Multiple Arms (3) - gain +10 to climbing/swimming, gain 1 extra attack (3/2, round down)

Multiple Arms (4) - also gain 1 extra attack, 2 total (4/2)

Multiple Arms (5) - no benefit (5/2, round down), 2 extra attacks total

Multiple Arms (6) - also gain 1 extra attack, 3 total (6/2)

Where multiple arms (3) means you have 3 arms.

The BC rules say that with Multiple Arms you need Two-Weapon Wielder to attack, which is part of what is throwing me off.

The Tyranid in question, if it had Two-Weapon Wielder and one set of weapons (say, Scything Talons), it should be able to make two attacks with them, right, as part of a Multiple Attack? (since there is one on each arm)

Then the Rending Claws get added on top of this? Can it make two more attacks with them with Two-Weapon Wielder, or just one more attack with Multiple Arms?

OK, after some thought, I have decided that the Tyranid in question gets 4 attacks:

2 from the two scything talons + 2 for the two rending claws, all with -10 because it has to use TWW. That is a lot of attacks.

I... think that is right.