Definitely new legal territory, but the laws are bent to the will of the powerful - those with lots of money ... even if courts side with you initially, legislation will come about to force the courts to do what 'they' want. I hope you build an app with full functionality and get it out asap ... then take down the website - I don't want to see a brilliant guy like you dropped into a hole like they did (and are doing) with so many others. PLEASE, consult a few lawyers asap.