Look at the packaging for your batting (wadding?). It will tell you how far apart you can safely quilt.
When you pin the sandwich, you need to tape the backing down so that it is taut, but not stretched. Smooth your batting over, then the top and use lots of pins. You should not be able to put your fist down without touching pins. Then remove the tape. I would try SITD using your walking foot on a practice piece. It sounds to me as though the foot is not installed correctly. Check your owner's manual. There's either a prong or a fork thing-y that needs to go over or around the screw that holds the needle in. Again, work on a practice piece before trying it on your quilt. Don't be too discouraged, it's all part of the learning process.