If you plan to buy a lot on which to build a home, have a builder (preferably the one you plan to use) review any properties you are considering, to help you select the best site for the home you want to construct, or to suggest the types of homes you could build on the different sites.
One way to fix a loose screw in wood is to remove it and then insert toothpicks or burned wooden matches with a coating of wood glue into the hole. Allow the glue to cure, then cut flush and re-drive the screw. You can also insert a plastic wall anchor into the screw hole. When you put the screw back in, it will expand the anchor and will hold solidly.