Some Wi-Fi networks such as those you find on coffee shops, when connected to, automatically redirect you to a web page where you will need to do something (enter credentials, accept terms of service, etc) in order to access the internet. Is the same possible with an android hotspot?
You might be able to, if you wrote an app for it. I'm not sure if the APIs are available though, and whether it would require root or not as I dont develop for android. As far as I know, there is no way to do it on stock android. EDIT: You would need to implement RADIUS or similar. Trust me, it is complicated even on platforms FreeRADIUS supports. You might want to just get some enterprise/pro-sumer wireless access points and use those (Ubiquiti Networks are good ones to look at)