Briefly, the commands you've used aren't creating the arrays on partitions, but rather on entire disks. This means you're not able to set the partition types to Linux RAID, likely giving the system a good deal of confusion as to exactly what devices your hard drives actually are. Also, smartmontools only checks the SMART status of physical drives; it won't recognize a RAID array, because a RAID isn't actually a hard drive, but rather a virtual grouping of hard drives. SMART data is only available on each individual drive. I suggest you run the extended SMART scan on the drives before assembling the array (though it'll take you an hourish to run on both drives I suspect.) The command is:
smartctl -t long /dev/sdb
and then running
smartctl -HcA /dev/sdb
on both of the drives. The first command runs an extended self-test, the second command spits out both it's 'general' self-assessment, and the raw data behind that assessment. Pay attention to the RAW_VALUE of Reallocated Sector_Ct and Current_Pending_Sector values, as these are common indicators of an old or defective hard disk. My personal recommendation is to use the Ubuntu live DVD (I like 10.04 and 10.10) as the 'Disk Utility' offers a nice graphical interface for running these tests, so you don't have to mess with the command line if you don't wish.
You'll need to start from scratch with the RAID again. Use fdisk (or, my preference, gdisk to create a GUID partition table, as GUID is more robust and the direction of future filesystems) and then create one partition on each drive. Make sure the partitions are the same size (if the disks are identical in size, then you can just create one partition on each drive that spans the entire disk) and assign them the disk filesystem ID of fd (or fd00 depending on if you use fdisk or gdisk; using the 'l' command should print out the hex filesystem types in either case.)
Once you've done that, you'll be able to create your new RAID without any trouble. There's a very good tutorial on how to set up your RAID here, including a few thoughts on chunk size: http://tldp.org/HOWTO/Software-RAID-HOWTO-5.html