So to fix this your going to add how many cubic feet to you conditioning bill and of coarse you will have return air from there, so any future problems with mold or moisture will be shipped directly into the home. Put in the perimiter drain at the footing level and waterproof the foundation on the outside. This wheel was invented hundreds of years ago and works fine. Stop the water from getting in and you have no problem. There are salutions to the venting problems you have but I doubt if you will need any thing after you stop the water.