I think this could be really cool. If the group dynamics work out-- and I think that small-group would be ideal here-- then the freeform notion would be outstanding. Could we discuss with the GM what we "want" the outcome to be, privately, then write it in a freeform-type flow?
As for the "intensity" of the story, I'd be happy with light or bd, but 'extreme just to be safe' kind of defeats the purpose of having 'extreme' anyway, unless there's a strong push from the players/GM for some extremely graphic content.
Setting would really benefit this story well-- it would be awesome to have it in a cool town with lots of grim history but a cool nightlife. If it's America, I'd suggest New Orleans, Savannah, Baltimore, or LA? Maybe other ideas? Or if in other countries, I'm sure there's a million choices, but we can discuss ideas and I can do some research.
Personally, I may get gory with description of horror or combat at times, and really graphic with some details regarding erotic content, but I gravitate away from the most extreme stuff that would qualify as Ex with a big E. If I could apply for this game, and the group dynamics work out well, I'd most like to see a small group, GM controls 'outcome' with player input, and all parties contribute to the flow of action. If I could ask for specific erotic elements, they'd be some light NC with coercion and maybe a little mind-manipulation, group sex, maybe a 1-on-1 building, awkward, but satisfying relationship too?