i) SmartRoam+ = we don't have a huge amount of documentation on this feature, however I believe it is an AP-level feature, as it is mentioned on the DataSheet for our latest AP, the R730. Ruckus Cloud is effectively a huge SmartZone deployment and SmartZone leverages SmartRoam+ technology. https://www.ruckuswireless.com/rucktionary/client-roaming-and-smartroam
ii) DHCP will need to be on a separate server in your local network. Ruckus Cloud is only managing the Access Points it isn't providing off-site network services like DHCP, DNS, NAT, Routing, etc. Also DHCP is a layer 3 service (IP), the APs are Layer 2 (MAC) devices. That said, sometimes controllers can perform limited Layer 3 functions, such as a basic DHCP server.
I hope that helps,