(1) /boot partition can not be XFS (so, go for ext3).
(2) XFS is especially good if you are going to have really large files.
(3) As you said, partition layout suggested by the openSUSE installer is generally not good.
You are right in saying that one needs to have a separate /home partition so that the OS can be upgraded, re-installed etc. at a later date by not formatting the /home.
Since you are going to have only 4 partitions, choose just primary partitions.
But, since you have a RAID5 array, you must be having a lot of disk space (I presume). If that is the case and if you want to have more granularity with more partitions in the future, create 3 primary and multiple extended partitions.
Realize that no one file system or configuration gives you the best performance in all scenarios. XFS can give you speed increases over Ext3 in some cases, but if you work with many small files, maybe Reiser3 is a better choice. Alternatively you can configure and use JFS (I use it, even though there are warnings).
I often go for a very granular approach with the following:
true, but it does do fairly well for small files. I tend to avoid non journaled file systems as a matter of course. There are times I have had to retrieve things from /tmp and if there were an issue, I’d prefer a journal.