I had this same question about 20 years ago and I called tech support at Nutone. They said that a fan/light combination unit was not a recessed light and did not require the rating or label. They did tell me that their unit was tested with R-19 insulation above it.
the Broan fan/light I use has an inline t-stat that pick up power off the light switchleg so if the 100watt bulb is left on without the fan, it will kick on by itself to vent the excess heat. If the light is on with the fan obviously heat is not an issue. I have never heard of an exhaust fan that you can't put insulation up to.