Is there any provision for ventilation within the rafter cavities (for
example, soffit and ridge vents)?

Many cathedral ceilings have some provision to circulate air under the
roof sheeting, for example:

http://www.cwc.ca/design/building_sc...igure-6.12.gif

and if yours has such provision, you don't want to defeat it by
stuffing the space with insulation.

Michael Thomas
Paragon Home Inspection, LLC
Chicago, IL
mdtATparagoninspectsDOTcom
847-475-5668