D&D Official FAQより

Q:Whirlwind AttackとCleave同時使用可能ですか?
A:Np.Great Cleaveあれば、斬った数だけCleaveできる。

> Do the Whirlwind Attack and Cleave feats stack? For
>example, can I use Cleave to get extra attacks if a
>Whirlwind Attack kills one of my targets?
> You can use Cleave only once a round. If you have the
>Great Cleave feat, however, you can cleave each time you
>drop an opponent, even when the opponent drops in a
>Whirlwind Attack. (When a foe drops, resolve the >extra
>cleave attack before finishing the rest of the attack rolls >in
>the Whirlwind Attacks.)

D&D Official FAQより

Q:Whirlwind AttackとTwo-weapon Fighting同時使用可能?
A:Np.　主武器でWhirlwind Attackと同時に、逆手武器で攻撃でき
　る。

>How many attacks would a character with the
>Whirlwind Attack feat get if she were attacking with
>two weapons? What if she has Ambidexterity and Two-
>Weapon Fighting? What if she also as Improved Two-
>Weapon Fighting?

> If you don.t have Improved Two-Weapon Fighting,
>you get one attack against every foe within 5 feet, plus
>one attack for the second weapon. The Ambidexterity
>and Two-Weapon Fighting feats reduce your penalties,
>but they don.t give you any extra attacks.
> If you have Improved Two-Weapon Fighting, you get
>one attack against every foe within 5 feet, plus two
>attacks with the second weapon.
> In either case, you must use your primary hand for the
>Whirlwind Attack, though you can decide which weapon
>will be .primary.. Note that your two-weapon attack
>penalties apply to every attack you make during the
>Whirlwind Attack.