As far as I know you can use the current version of SDK, but you can not use all functions . You are limited to the functions provided by your Nero 5.5 version. You can find which functions (also parmeters and so on) supported by which Nero version In the documentation of the NeroApi.
As far as I see in the documentaton (page 62) is the media type DVD-R introduce in version 22.214.171.124. I assume DVD-R support starts with that version.