Okay, my initial guess was correct: the CRX320EE is indeed based on the LiteOn SOHC-5236K (so that'd mean that the CRX320ED is probably based on the SOHC-5235K, but that's another story).
1/ Your firmware, RYK1, is dated 25 Feb 2005 (half a year old). There are no known official Sony firmwares to update your drive with (no RYK2, etc.), since your dump of RYK1 is the first RYKx firmware I've seen.
2/ You can update your drive with a SOHC-5236K firmware, however (though this will technically void your warranty). The latest one available, RK07, is dated 31 May 2005, so it's a few months newer. That having been said, CD-RW/DVD-ROM combo drives are a mature technology, so it is unlikely that there will be anything radically changed or improved between RYK1 and RK07. If your drive is working okay at the moment, it is unlikely that you will see much improvement if you flashed to RK07.
3/ If you're looking for region-free, you can use LtnRPC to disable the drive's region protection and/or reset the number of changes left.
4/ If you want to increase your drive's DVD rip speeds (this will technically void your warranty), you can flash your drive with a firmware patched by OmniPatcher.