windows volumes

I am starting out with a raw disk which I partition with DeviceIoControl, but I need to assign it a drive letter for use, I found SetVolumeMountPoint which requires a volume.

Also a unique signature (dword) is attached to the master boot record structure, an msdn article stated this must simply be unique, is ther anything special I need to do with this- or just insure the value is a unique signature?

So:
Does the volume manager automatically assign a volume to the drive?

How do you create a volume in windows?
or
Is there another way for me to assign a partition a letter?
or
If automount automatically assigns a drive letter to the partition when I create it, how do I get the drive letter?

thanks.