Where am I able to get the pirate missions?

Unless I'm mistaken, last I checked, there were no Pirate Missions in EV Classic.

Are you thinking of EV Nova?

There are a few missions that allow you to work with the Pirates in EVC (only 3, if I'm not mistaken). You can get two of them at any Pirate port. I'm pretty sure the third one can be found in any bar, and you take a passenger to a Pirate port from there.

Destroyer E is correct: there isn't a pirate string , but there are missions doing drug deliveries and messing with Rebel and Confed convoys.

Yes. As said before, there are no pirate missions. The only mission close to involving the pirates is the delivery company mission string. I don't recall the name, but I believe that is had a lot to do with pirates. The last mission or one of the last missions is a big battle in one of the pirate systems.