The drain is easily fixed. just get a 3/4 inch bung valve and screw it right into the hole where your yap is now. if the hole is not quite large enough, use a file to make it just big enough to just start the threads. it will get tighter as you screw it in as pipe threads are tapered. make sure you get a plastic valve as the metal ones are quite expensive and for your application the plastic will last forever. you can get them at most places that sell plumbing supplies. if you would happen to make the hole too big just screw on a 3/4 inch conduit nut to the bung threads.