Not sure about the "how long it takes for a frame to render out" problem, but if you want to know how far along you are in a batch render, (providing you are rendering out frames and not a single movie like an avi), you can simply open the file you have your frames set to go to and watch them pop up. The reason Maya does not display the images or have an option that displays the images while or even after they are rendered is because it takes up a lot of memory, which will obviously slow down your batch rendering total time.