I honestly think disregarding essay 3 in the way mentioned would be a big mistake. Two essays with such a clear structure and short word count are putting on to a clear, precise approach. There are schools with a lot looser word count on less topic. Got to think them out.
I have some ideas for what I am going to do for three. It reflects me pretty well, and should be quite fun for me to put together. By all means just write an essay for three. It shows LOADS of creativity. Maybe just copy one you wrote for another school and do a find-replace...
I am annoyed that they want the proper transcripts, as getting one copy from my faculty for my significant years was enough work in itself. I can't see why they feel the need to take in the real versions.
As for jobs, I may well mention my bar work through University, and maybe mention some other bits. But bear in mind it asks about bonus, and will be seeking relevance.