you'd have to look in your attach options. You can blend the two together or you can have them connect as-is. Also a few other options in there. After attaching one side. Delete it history and instead of attaching the other side, you'll have to do what's called "Open/Close Surface." Because once you've attached it at one end, it is no longer 2 seperate objects, and you cannot attach an object to itself. So, you'd have to "close" it. Again, look in the options and choose Connect or Blend, depending on what you want.

You can duplicate your profile curve however many times you want and loft a surface between them.

Extrude has been explained in other threads many times. I'm sure you should be able to find one.

Good luck.