By formulating your research questions as concretely as possible, you clearly define your work and you have a clearer idea of what you have to do.
Research questions may change! Maybe you will find out during your project that your direction for a solution will not work at all, or that there is another possibility with a greater chance of success. Do not get stuck in your original plan because this is what you happened to have thought up at the beginning of your project. Keep focused on the final goal. Adjusting your plans based on insights gained in the mean time is a must.
At the end of your project, look back at your research questions and reflect on what was or was not useful and what you overlooked. That way you will improve at thinking up and formulating research questions.
Do not forget to answer your questions and apply the answer to your final solution! If your question was important enough to ask and put time into researching it, then the answer must also be available somewhere, and it should have an effect on your final solution (relevance!). The answer could, for example, be included in a research report or as part of a design or test report.