Blossom,
Sorry for the delayed response. To answer your questions:
YES, you need to cite your sources in text. THe exact protocol varies from field to field, but it might be something like "...provides convincing evidence that the Earth is round. [2]" In your bibliography, you have a reference numbered 2, so the reader knows where to look for more information. Take a look at journal articles in your discipline to get aquainted with the citation format for your field of science.
In a sense, yes, it does matter whether your project is, as you term it, "abstract" or "practical." The fact of the matter is that every bit of science is practical. The judges are interested in how thourough you are in doing science and the applications for your work. It is imperative that you understand why what you are doing is important. It doesn't need to be life-changing or revolutionize the world of science, but you need to understand your work's importance. For instance, I study the chemical changes happening when asteriods and planets collide. Is that going to cure cancer or stop global warming? No. But in the field of planetary science, understanding these chemical processes is crucial to understanding how the solar system has evolved. Become familiar with the applications and implications of your work.
The text on the display board should be highlights of your project, a summary of your work. The research paper is much more detailed and arguably more technical. We can clarify this question in further detail later, but let's not worry about the display until we have the actual project done. First things first