For removing the bearing, you might try putting the plate in the freezer overnight, then using a propane torch to heat the aluminum plate around the bearing while pressing it out.
Steve I don't know how much material you have available, and I know money is tight, but if you could hold something else in the chuck, with holes tapped into it to match holes in the part you want to bore, you could first mount that piece and face it square, then bolt your part to it -- it is now square, and then bore your holes. Think of it as a temporarry faceplate.
My first faceplate in my homemade lathe was just a piece of 1/2" pipe screwed into a pipe flange. I mounted that, turned the face of the pipe flange square. Then I screwed to that a 7" dia 3/4" plywood disk, faced that.
Then I mounted my actual rough cast 7" aluminum faceplate blank to that, and faced it, both sides, after turning it around.
Then I bored it and had myself a true aluminum faceplate which replaced the temporary rig with drill rod for an arbor.
Then I trued the edge of the new faceplate did a minor cleanup of the face, and all was well.