IF a shield uses I2C, please list the ADDRESS or ADDRESS Range usable.
For things like that I list it in the "notes" section that appears directly below the shield diagram, but only if I know what it is. I've spent many, many hours going through circuit diagrams and documentation for shields trying to find info like that but I can't do it all myself! If you have information about any particular shields please click the link at the bottom of the page to send me a correction.
Also how might one develop a spi shield and give a few choices for CS/SS pins?
That's entirely up to you. The easiest is probably to run something like a 2x3 male header, with all pins on one side connected to the chip CS and the other three pins connected to three digital lines. Then users can put a little 2-way jumper header in place to select which digital line to use.
Jon
Security Sensor Shield: Security Sensor Shield for Arduino | Freetronics