Additional information you'd like us to know about you?

Answer 1

This give you the opportunity to tell your prospective employer things about you that may not have been covered by their questions. The key bit is "you'd like us to know".

Be truthful in what you say and be prepared to be questioned on what you have written should you be invited for interview.

Answer 2

You may feel you are suited to the job you are looking for in ways that the application form does not cover. application forms tend to be somewhat non specific as they are given out to cover different people and jobs. so if you feel you would like to add something to the form you are filling in that you think may impress your prospective employer do so because it always impresses the boss when you look like you are putting in a real effort, even if it doesn't seem important to you.