First next time please make your title more descriptive you will get more help that way. You might even want to change it now.
There is a classified module that is available. I think itis over at
Nukestyles but I could be wrong. The one I'm thinking of has been ported to work with Nuke anyway. If you don't find it let me me know and I'll see if I can find it again, unless someone else knows.
You might also be able to use menatos gallery to do the same thing. It is the gallery that is used here. When you load images, you can put a description in there. I don't see making the block a center block a problem, except that if you want more then one image to show up in it, you would have to modify the block itself, because it is a random image block.
I haven't heard of anything specifically for real estate.
You're right btw... having a test site is one of the best things you can do. Then if you break it, it's still all good.