
1. Yes, there are. If you have unpacked all game files then check the libraries folder. You'll find there several xsd files. the common.xsd and md.xsd are most important. For XML scripts check the aiscripts.xsd and in the main root of your unpacked file folder also the scriptproperties.html. More info you can find in the XR S&M forum.
2.As I wrote in the sticky here (I know it's potentially invisible

3. The ? maps the value to binary, i.e. 0 or 1. if it does not exists or if it does, respectively.
4. The @ maps the value to a Boolean, i.e. false or true, if it does not exists or if it does, respectively.
Cheers Euclid