1: Yes they can talk with each other.
2: I know this isn't exactly what you are wanting, but thought it applies somewhat.
http://cyclone.com/products/expansion_systems/600-2703.php And they have smaller ones as well.
As far as not using a PC as the main host, you can use the Stratix 4 as the RC like you said, but I don't know of any Dev-boards that have a Stratix 4 already on them configured as the RC, well, for that matter i don't know of that many dev boards with a S4 on them. You could always build your own...but i guess that wouldn't be called a devboard and would probably just be called your product.