The drawers are very simple to make. First, cut the drawer bottoms from ½" plywood. Make them about 1/16" narrower than the distance between the dadoes and full length. Cut strips of solid wood or plywood equal to the inside depth of the drawers you want and cross-cut them to length. I assemble the drawers with glue and nails. Note that to store a 5" tall object, you don’t need a 5"-deep drawer – you just need 5" of headroom.
Yes, another website with a simple design. However, they are high in content and offer great woodworking plans for a whole range of interesting and easy to do projects. iBuiltIt.ca has been around for a while, and is a well-respected online real-estate, mostly because of their quality plans. Their plans are ideal for both beginners and experts alike.
You can also use Google image search to research a project. Unlike the PDF search, the image search provides a photo of what the project will look like, which is helpful in determining if you want to pursue building it. By doing an image search for how to build a step stool, you will have a ton of options that all lead to woodworking plans of various quality. (The how to part of these is important—otherwise you’ll just get pictures of step stools.)