Sony DRU-500A newbie questions

Just curious, about my new cheapo-buy hardware - Sony DRU-500A

  1. Is SONY DRU500A a proprietary Sony product ? Or it is a rebundled drive of other manufacturer ?

  2. Am i right. In North America, liteon sell LDW400 which is unlisted on liteon www page. Is it a DRU-500A rebundled by LiteON ?

  3. For this time, with firmware 2.0g what are the diffrences between 500AX and 510A ? Only DVD+R 4x writing (500A to 510A) ?

  4. Does anybody of You know a www page where OEM releases of ODD are listed ? (traxdata > liteon, etc.)

Thanks!