Unleashed Multi-Site Manager (UMM) will allow you to manage all the Unleashed APs / networks from a central location as long as UMM can reach Unleashed network(s). Here are answers to your questions from Unleashed point of view.
1. Yes, users can be redirected to captive portal for initial authentication. After successful authentication, users data traffic will go directly to intended destination - aka Local Break Out (LBO).
2. Yes, you could have a centralized AAA and get users authenticated by this AAA - assuming (as you said) those AAA servers are reachable from each Unleashed network.
3. Using UMM, you can get into any Unleashed network that is managed by UMM as UMM supports Single Sign-On. Pl make sure UMM, Unleashed networks, and the client device from which you are accessing are IP reachable. UMM will allow you to monitor, manage, and make config changes by getting into Unleashed Master from a central location.
4. Radius Accounting is already supported - starting version 200.5 (released couple of weeks back).
5. Yes, L2 roaming is supported within each Unleashed network.
As far as cost is concerned it depends on how you compare Ruckus Unleashed and Ruckus Cloud WiFi.
Should you have more questions regarding Unleashed or UMM please feel free to reach me at '
nat.chidambaram@ruckuswireless.com'.
Best Regards
-Nat