How can I determine what RAIDZ level my volume is using?

zpool status will list all of the drives and their layout, including mirror/RAID level.

In your case, raidz1-0 means you are running raidz1 and the group number is 0.

You were running the right command. zpool status -v is the correct way to understand what a ZFS pool is comprised of. A better example, as the vdev groups are enumerated, beginning with 0. Note the multiple mirror groups and single raidz group below:

[root@MDMarra ~]# zpool status -v
  pool: vol1
 state: ONLINE
  scan: scrub repaired 0 in 0h32m with 0 errors on Sun Feb 16 17:34:42 2014
config:

        NAME                        STATE     READ WRITE CKSUM
        vol1                        ONLINE       0     0     0
          mirror-0                  ONLINE       0     0     0
            wwn-0x500000e014609480  ONLINE       0     0     0
            wwn-0x500000e0146097d0  ONLINE       0     0     0
          mirror-1                  ONLINE       0     0     0
            wwn-0x500000e0146090c0  ONLINE       0     0     0
            wwn-0x500000e01460fd60  ONLINE       0     0     0
          mirror-2                  ONLINE       0     0     0
            wwn-0x500000e01460e7f0  ONLINE       0     0     0
            wwn-0x500000e0163a9990  ONLINE       0     0     0
          mirror-3                  ONLINE       0     0     0
            wwn-0x500000e014611300  ONLINE       0     0     0
            wwn-0x500000e0152a3550  ONLINE       0     0     0
          mirror-4                  ONLINE       0     0     0
            wwn-0x5000c5001cdf0113  ONLINE       0     0     0
            wwn-0x500000e014605e30  ONLINE       0     0     0

errors: No known data errors

  pool: vol2
 state: ONLINE
  scan: scrub repaired 0 in 0h0m with 0 errors on Sun Feb 16 17:03:28 2014
config:

        NAME                        STATE     READ WRITE CKSUM
        vol2                        ONLINE       0     0     0
          raidz1-0                  ONLINE       0     0     0
            wwn-0x5000c5000c245113  ONLINE       0     0     0
            wwn-0x5000c5000b307057  ONLINE       0     0     0
            wwn-0x5000c5001cc4b45b  ONLINE       0     0     0
            wwn-0x5000c5000b30d58b  ONLINE       0     0     0
            wwn-0x5000cca00a0ea20c  ONLINE       0     0     0
            wwn-0x5000cca00a1a63ec  ONLINE       0     0     0