I am still in the middle of making similar repairs but I do have a recommendation if you don't have your own tools for fabricating sheet metal. Specifically for picture number 2. There are some complicated bends and angels. Make a pattern with poster board. Cut out the pattern using 18 gauge sheet metal. Take it to a sheet metal shop (one that manufactures/fabs up heating and air condition duct work). The will make quick work of bending the sheet metal for you into a suitable patch.
