I think I'll start by saying this: Your game's functioning set-up will not be for everyone; learning new tricks can be scary and, sometimes, off-putting. That being said, don't let that fact alone discourage you, because the ideas you're working with could be really fun and interesting, broadening the core of a writing-based RPG, if done well. Using Batman as a setting to try this sort of thing out is, imo, a very good idea, and based on what you've presented it seems like you understand that and why that is.
My one/only real piece of advice would be this: Guides, guides, guides. You're working with a lot of elements that will be unfamiliar territory for some potential applicants (ie. the ones who only do writing-based RP), and having well put together information, guides, and examples of that territory will make the new content less overwhelming.