1. The 9pi image has a cpu kernel but its file system is not completely configured for use as a server. How you do that will depend on whether you are adding it as a cpu server or file server to an existing Plan 9 network, or using it as a self contained cpu + fs + auth server. The wiki has quite a bit on this subject - see http://plan9.bell-labs.com/wiki/plan9/configuring_a_standalone_cpu_server
In this respect the pi is just like any other Plan 9 machine. The 9pi image starts with 'pi' instead of 'bootes' as the hostowner / authid, but you can of course change this with auth/wrkey and auth/changeuser. As Erik suggested, you can run /sys/lib/newuser to create the home directory for user 'pi', or whatever other name(s) you choose. 2. Once you have a server set up to publish its fossil connection, your client can use it as root. If the server is running ip/dhcp and you have set up the required information in /lib/ndb/local, you can just reply 'tcp' to the boot prompt. Otherwise you can reply 'tcp -g r.r.r.r c.c.c.c' where r.r.r.r is your router's ip address and c.c.c.c is the client's desired ip address, and you'll be prompted for the ip address of the server for fs and auth. To cut down on prompting, you can define things like bootargs=, fs=, auth=, DNSSERVER= and user= in cmdline.txt - see plan9.ini(9) for details.
