Are you using controller based or the autonomous ones. If you have controllers, then its really easy. Just set the security policy on that WLAN to web-auth. Then set up the web login page and create accounts via the WLC.

I believe thats all you need. But if not, in ACS, go to group setup, select the group that you are using for wireless clients. Click edit settings, scroll down to max sessions.Max SessionsSet the maximum number of sessions available to groups and use...

In your WLC. Go to Security, AAA, user login policies. You can set the maximum number of concurrent logins for a single user name there.

Where do you see that you can only have one device type per ip pool? Unless if I am missing something or its something on the newer codes, I have multiple device types on the same ip pools.

I believe its up to you. We have multiple models running in our sites and they work fine.