I am remodeling my basement. There is a common wall between the finished area and an unfinished storeage area. Since there are outlets on the wall facing the finished area I will put drywall on both sides to cover the Romex in the wall. I will be installing a switch for lighting in the unfinished area, on the wall that will have drywall on both sides of it. It will be inside the drywall in a box with multiple switches. Can I use Romex? Since the light it will be switching is in an open area without drywall, can I run Romex in the wall, then out to conduit to the light fixture box? Is there a limit to the length of conduit I can use with Romex in it? How do I get the conduit in the wall, through the top down? How far does it have to go in? Do I need to have a conduit terminator end (end cap with a clamp) at the wall end? at the box end?

I will be running regular THHN wire in any other exposed areas in conduit.

Run Romex through out, no need for conduit unless there subject to damage. That's damage that you don't normally find in an unfinished basement.

Not sure why you want to go to conduit. You could run the Romex all the way. Running Romex inside conduit is allowed as protection, but you have to secure it so it can't be pulled out of the conduit.