Since you are talking about laying the carpet on below grade concrete (under the level of the ground around you), you really have to plan that it might get wet at some time. One solution is to use indoor/outdoor type carpet. If you do this, you will be concerned about the dust when cleaning, and any "bumps and lumps", but I would not bother about getting paint up. Another "For What It's Worth" is that our basement carpet is not glued down, except right at the doorway. We have had no problem with it moving around and I tried to keep the glue to an absolute minimum.