...I just want to make sure I understand this correctly:

If I have a cannon upgrade for a B-Wing, I can use either the cannon upgrade card's attack (assuming I have a target within it's firing parameters) or I can use the B-Wing's primary weapon attack (assuming I have a target within it's firing parameters) during a match, correct?

Or can I only use the upgrade card's attack and never the primary?

You can use either one.

In a given round you can only use one of them, you can't fire both at the same time. But you can switch between them from round to round depending on the circumstances.

...I just want to make sure I understand this correctly:

If I have a cannon upgrade for a B-Wing, I can use either the cannon upgrade card's attack (assuming I have a target within it's firing parameters) or I can use the B-Wing's primary weapon attack (assuming I have a target within it's firing parameters) during a match, correct?

Or can I only use the upgrade card's attack and never the primary?

You want to take it a step further lets also equip a Torpedo of some kind. Now the Cannon and Torpedo are both secondary weapons and follow most of the same rules for use. To say you can only use the Cannon OR the primary is just like saying you have to use the Torpedo OR the primary.

Now where one may get confused is when someone is running a YT-2400 with the Outrider title. That title SPECIFICALLY prevents the ship from make attacks with its primary weapon as long as it has a Cannon equipped. Its use may be common enough that people may start thinking it also applies to other examples.

Also, cards like Gunner and Luke require the `second' attack to be made with the ship's primary weapon. (So don't put Luke or Gunner on the Outrider)

Also, cards like Gunner and Luke require the `second' attack to be made with the ship's primary weapon. (So don't put Luke or Gunner on the Outrider)

Which is a big part of the reason you don't see those upgrades used with the Outrider and very rarely with any other YT-2400.