1) You will probably find most people will be more willing to help you if you write in more coherent language.
2) Don't worry about where other people are up to in the course, every school works to different timetables. You only need to start talking to people from other schools if you feel your teacher isn't teaching you the material you
are covering properly.
3) A list of projects people are doing this year can be found in
this thread, but don't just rip off someone else's topic. If you are doing History Extension, you must be interested in history ... so just have a think about what specific areas you like and then see if you can get a topic from there. Otherwise, leaf through general history publications and see if something grabs you.
4) Yes, the essay is meant to be historiographical, rather than historical. That is, you should be mainly writing about how historians have looked at the event (and
why certain historians have looked at it in certain ways, eg. as a result of personal or ideological bias). That said, a brief historical introduction to the topic doesn't hurt in case the reader doesn't know a lot about the area.