I want to finish my second floor in a fairly new home.
Lets start slow and see how it goes.

The room ~700 square feet is now vented to the outside through a vent on the
Side of the house and a hole cut in the plywood sheeting leading to a dormer with an octagonal vent. Make sense?

So how do I properly vent this space? Eventually I want it to be a bedroom with a bath and small office area? I have a heating/cooling device in the room but no
Duct work is run to this area.

The space is supposed to be ready for plumbing. I see hot and cold water and a large vent pipe that goes out the ceiling.

Anyone willing to give me a hand with this?

Thanks much,
Kent

This sounds like an A-frame building. If your making the 'loft' into living space, you don't need the octagonal vent.

I would connect the future bathroom vent to the large vent pipe that goes out the ceiling.

Try insulating the hot water pipe and presto- done!