I would agree with Knurpht and split /home into /home and /backup or something else, but up to you really.
for backup I use
SourceForge.net: G4L, as I find the opensuse backup from yast sort of a joke, sorry
g4l might be a tad complicated at first but once you get the hang of it you will be fine
as for what filesystem tbh just stick with the default if your new which is ext3 for 11.1 and I think ext3 for 11.2-factory. You can speed ext3 a bit up by adding noatime,nodiratime to the options for the filesystems in /etc/fstab, that means no time will be changed when you read/access a file or directory.
not sure what you mean about games, but most of what you will install will be on /home, I never gotten over 6gb on / myself.