The first thing to do is cut a hole in the top. With all the rubber coated on the outside you may not want to use an angle grinder. I converted a rubber coated keg quite a few years ago and I think I used a drill and a sawzall to cut the hole in the top. As for the size of the top hole, you may want to create the hole the same size as a pot cover you already have.
Now for the valve and fittings. Go to Bargain Fittings
and get a weldless bulkhead fitting kit. You may have to go with a cooler kit. It depends on the width of th e keg wall. Im thinking the rubber coating is about 1/4"....you should be able to get all ss for $28.00
As for the false bottom, there are alot of different options you can got with....hope that helps