On the upgrade card it says spend target lock and discard this card to preform this attack twice. Do you have to do that or can you keep the target lock and card by preforming the attack once?

Sorry mate.
With Cluster Missiles, if you have a Target Lock, you may either attack with your primary weapons and not use your missiles, or discard the card to attack twice.
There is no middle ground.

So the attack twice means you can roll twice to attack? Sorry. I've never played clusters, but just read this card.

So the attack twice means you can roll twice to attack? Sorry. I've never played clusters, but just read this card.

Correcto!

They're great for attacking at range 3 as the Defender doesn't get a range attack defence bonus.

So the attack twice means you can roll twice to attack? Sorry. I've never played clusters, but just read this card.

Correcto!

They're great for attacking at range 3 as the Defender doesn't get a range attack defence bonus.

Cluster Missiles are actually pretty worthless for attacking at range 3 as they can only attack at ranges 1-2.

Cluster missiles are best used against targets with low agility, since both attacks roll separately. Additionally, an effect like Marksmanship would apply its modification twice, so you could potentially score a critical hit from both the first and second volley of missiles (since each volley is a separate attack, and Marksmanship applies to "all attacks you make this round").

Cluster missiles are best used against targets with low agility, since both attacks roll separately. Additionally, an effect like Marksmanship would apply its modification twice, so you could potentially score a critical hit from both the first and second volley of missiles (since each volley is a separate attack, and Marksmanship applies to "all attacks you make this round").

So I could conceivably attack, re roll misses, attack, reroll misses??

Cluster missiles are best used against targets with low agility, since both attacks roll separately. Additionally, an effect like Marksmanship would apply its modification twice, so you could potentially score a critical hit from both the first and second volley of missiles (since each volley is a separate attack, and Marksmanship applies to "all attacks you make this round").

So I could conceivably attack, re roll misses, attack, reroll misses??

Marksmanship does not allow you to reroll. It does allow you to change eye results during all attacks.