Recessed light fixtures can be a major source of heat loss, but you need to be careful how close you place insulation next to a fixture unless it is marked. "I.C."—designed for direct insulation contact. Check your local building codes for recommendations.
You can buy several types of guides that attach to your router so you can create decorative circular grooves on the surfaces of wood projects, or you can make up your own. Besides making grooves of various designs by switching router bits, these jigs can also be used to make circular cut-outs. Instead of cutting only partly into the surface, continue with shallow passes until the cut is all the way through the wood.