32 vs 64 bit is a question that you really should answer. If you are using applications that are only 32 bit then be prepared for the changes if you go 64bit. If this is a general purpose type of server (MySQL, Apache, ect ) then I suggest you go 64bit. In my world (eg everything that I do) the 64bit MySQL works SOOOOOO much better then the 32bit version doing the same tasks. Some tasks you may not notice the difference in the slightest. I also have need of upwards of 8GB of memory so that obviously influenced my decision to go 64bit as well.
As for the partitioning, I don’t know what you are doing so I can’t give you anything more then a few suggestions. I personally always set aside 10GB for /. I also set my swap space to be 2x the amount of memory or 5GB, whichever is the smallest. If the box is going to be using a lot of temporary files I will set a large /tmp partition if need be. If it is a web server, I usually give /var/www its own partition. I have a few applications that use /opt extensively so on those systems I give a 10GB /opt. The rest of the space always goes to /home. It really depends on what you are doing with the system.
Probably not the definitive answer you wanted, but hopefully it helps ;-)
Have fun with that server!
We just ordered a new 1U server that will operate in a Colo setup.
Xeon Yorkfield X3350, quad 2.67Ghz, 12M L2, 1333fsb