On the xserve do you have the FQDN fully qualified domain name in server admin? You should be able to connect by clicking Add server and entering 127.0.0.1.
As for RAID Admin it only works if the RAID is connected via ethernet. It sounds as if you either haven't connected the ethernet, your network config has changed or you had them on DHCP. Try clicking Add on RAID admin then seeing if it sees the 3 RAIDS. It's always best to set these to a fixed IP.
Hope that helps