Here are some ideas
Sony Vegas is good editing program that supports a wide variety of media formats. Since your post seems to imply that the info to be projected is able to be set up in advance, you could just edit a program that you then ran. Another easy way to crop a lot of stuff is to build in essence a black frame mask that you then green screen in the software your content, so you then get a video blacked border. As mentioned it is possible with a bit of experimenting to make a mask that you put on the
lense of the projector, since there aren't any shutter systems usually it is just by experimentation with a piece of cardboard that start with your shape in a very small size and then just keep enlargeing until you get the right size.
Media servers are very pricey, if it really is slides power point coud be used with the masking on the projector. once you get the pattern set you could move to something that is more stable and heat resistant. You do have to be careful not to damage the
lens
Sharyn