1) Not expressly mentioned as a problem, but it would be best to export from InDesign to PDF and print from Acrobat.
2) There are too many variables to answer your question with specificity. Your computing platform, printer type, and printer driver all might affect how you'd go about printing to a non-standard media size. A typical Windows-based Postscript printer driver, for example, has an "Advanced..." button on the Paper/Quality tab that launches an Advanced Options dialog in which the Paper Size: menu includes an item: Postscript Custom Page Size. But whether you have this particular avenue to setting a custom media size can't be known without more information.