Where are you redirecting users to? external hosted or local access? The WiNG captive portal is very easy to set up. As for the T&C page, not sure of the size limit. Use the GUI to create.The hardest part for me was getting the certificate distributed via the File-Sync feature and the Firewall to open the proper port(s).
The other new feature that we have not gotten into yet, but are starting to investigate is the E-Guest feature. Similar to the captive portal, but not as intrusive for the customer\client.
Good luck on the Captive portal. Extreme Support is great at helping you get this set up and working. Suggest reaching out to them.