A fire rated downlight is a downlight that has gone through fire resistant testing to determine how long it will protect against a fire. These types of downlights are created to block a hole that is cut in the ceiling. An intumescent pad on the downlight blocks the hole and expands when it reaches a specific temperature. This will help slow the spread of fire along your ceiling or walls.
Yes, LED downlights are dimmable. However, it is important to check the packaging to confirm if your specific model is dimmable. The specifications are mostly in the description or technical page of the product. American Lighting’s Fire Rated Downlights are dimmable with most TRIAC dimmers.