1, If you have a Big Lots around you they have a very cheap 22 inch round grill that the lid from will work. I had the same problem with mine. since the diameter varies for 55 gallon drums you may have to do minor alteration. 2, I used 3 air holes for mine, each was 1" ID x 3" steel pipe, don't forget the pipe caps, and you will need one ball valve to control the air flow in.
Hope this helps you out.