When and where was it used?
Linguistically, what came before and after it? Is there a "Norse" to contrast with "Old Norse"? How does it relate to Germanic?
What are your favorite works written in the language?
Anything else I should know about the language offhand?
The depths of my ignorance on this subject occurred to me yesterday after encountering this sentence, written about the Pilgrimage of Charlemagne, a wacky Anglo-Norman poem which flirts with the chanson de geste genre, but really isn't in all sorts of ways: "The poem cannot have been written later than the translation into Old Norse, unaninmously dated in the thirteenth century, which derives from something very close to, if not identical with, the extant Pèlerinage."
This Old Norse translation isn't mentioned anywhere else in the materials I have handy. Are any of you familiar with it?