what to do about squeaky floors
Much of the difficulty in stopping floor squeaks comes from the fact that people don't want to remove or damage their flooring to fix it.  There are special screws with heads that snap off and other gadgets to make it easy.

You have no flooring, so it makes it a lot easier.  Get some good, strong screws and go to town on the areas that squeak.  Screw the sub-floor solidly into the floor joists underneath until all movement and squeaking have stopped.  Also, walk around the area with heavy steps to try and see any additional movement that might not be squeaking yet.  Screw down anything that even feels like it might have moved.