Welcome to Just Answer and thanks for your question. The first question just requires a yes/no answer. They aren't asking you for your previous salary. They are asking you what salary you think is reasonable for the job you are applying for. The open-ended question simply asks you to describe any similar position you have held in the pst.
You can attach an additional page to your cover letter and resume/CV, or answer on the supplemental page question. As an example, if you are applying for a job as a first grade teacher, you can mention that you volunteered with Brownie scouts, or helped with your church's nursery, or worked as a teacher's aide. Any job where you actually were paid is even better.
1. It's best to ask for what the job is worth in your area. You can check www.salary.com for a range of salaries based on location.
2. They will consider your requested salary in conjunction with your education and experience and within the salary range that they have already decided upon. If their range is $35,000-56,000 for a teaching position, they aren't going to pay a second-year teacher $50,000.
3. There are $5K ranges in the salaries they listed, so you have some leeway.
Actually, you don't have to repeat it, you can just say "see resume."