Yorkshire pudding is a popover batter using the drippings of the roast as the fat. One can cook it as a popover separately in popover pans, but traditionally the batter is placed in the roasting pan when the roast is in its finally phase of cooking and baked until the pudding is nicely browned. One can also remove the roast and put the batter in the roasting pan. This is a good way to proceed because in the time it takes the pudding to bake the roast can set. Also, it won't overcook. Keep the door of the oven closed once you start baking the pudding.
If lwunderlich said that in Yorkshire they'd say, "You're not from round here are you". Not a question, just a statement. Popover and Yorkshire pudding batters are similar but the Yorkshire one is simpler, eggs, flour and liquid plus seasoning, and the best recipe I've found is from Delia Smith, you'll find it at http://www.deliaonline.com/recipes/r_0000000745.asp . Not sure about the kind of roasting pan as I always use metal, but I suppose corningware would work, but you'd have to make sure it was very hot to start with.