RAID-5 and Chunk Size, What Filesystem to Use?

I've been reading the Jakob Oostergard article...and it's amazing how easy this can be, however I may have been typing too fast....

I have 3 SCSI that are 36GB each and I created my raidtab to look like the following:

raid-level 5
chunk-size 128
persistent-superblock 1
parity-algorithm left-symmetric
nr-raid-disks 3
device /dev/sda
raid-disk 0
device /dev/sda
raid-disk 1
device /dev/sdb
raid-disk 2
device /dev/sdc

my question is (are)
1. is 128 ok for the chunk size?
2. if it's not ok, do I just stop the raid-device and re-do my raidtab file and then re-do my mkraid /dev/md0 command?
3. what filesystem do you recommend? All I'm using this server for is file
sharing with SAMBA...

thanks in advance....

Ermm...you didn't actually intend to have sda be both raid disks 0 and 1, did you?

--
Paul