Sorry for the late reply, I agree with the earlier discussions between you and Abishek.

As for characters, I think that by itself would be a huge discussion and so why not let's stick with Twitter character limit of 280? I'm sure they have done enough research to justify that number.

The category of story selection you've mentioned are interesting, I think the second set of common categories would do for initial version and may be expand based on user opinion?

Btw, off-topic; Did you post a new parent comment here or the thread automatically positions new reply in a thread as parent after some levels?