This video from green homes america provides a good overview of the air leakage issue with recessed lights and shows an actual top hat installation.
Insulation around recessed ceiling lights.
How to insulate around can lights.
The letters ic stand.
A number of manufactured products are available to provide clearance for insulation around the fixture but you can also build a box using scraps of rigid insulation or drywall.
If i replace those bulbs with leds will that reduce the heat enough so i can insulate around the existing lighting cans.