Thanks guys. I knew that scroll bar had to do something. And yes I agree, by default Maya should save all renders that could be deleted at will.Yes, there's also a trash image to remove it from the queue once you don't need to compare it anymore. I wish by default Maya would keep the images in the queue, and then you could trash them, cause it's hard to remember to hit keep image all the time.
Brilliant! Thanks Stwert, another mystery cleared up. I'm getting there, albeit very sloooowly.The background color I believe is under the camera attributes (panel menu: view > select camera > attribute editor) under environment color or something similar. I believe the background color should not be included in the alpha channel, so if you open up a file in a format that supports the alpha channel, the background should be interpreted as transparent (regardless of what color you set it as). Hope that helps.