To be honest I agree it should be short. Maybe like a dress with a slight tail? Tumblr the way I see it is about pretty pictures and sorta slutty... in a way however many have a lot of meaning especially when they do the typography.
Neither. I think something like this: [link] BUT with your flare and style added on. Tumblr seems to need something a bit more firm and strict, almost uniform like in shape. But that's just my opinion.