Sorry, I'm a little confused. The post may be about "why you think this community may be beneficial to people" [...]
or
"about your hometown. You may mention some rare facts, show unique architecture or sculptures, share your own art that relates to your hometown "
can I choose one of the two?
no, you have to do everything (1-7). #5 doesn't have to be long. Just couple sentences is fine. You can say 1. why you think this community may be beneficial to people, and/or 2. why you think you should join, and/ or what you expect from this community. Also, you may propose some ideas on how to make our community better if you want. just follow the directions.
Oh, I understand, thank you very much!