The answers to your questions are
1. Although the center of mass and center of rigidity are not printed in the tables like those in the post processing mode, but these can be printed as part of the analysis output file. When one defines a rigid floor diaphragm, the center of mass is automatically printed. One can ask the software to print the center of rigidity by adding the command PRINT DIA CR.
2. Yes you can. An example file is attached.
3. Yes you can as long as you have the floor diaphragm defined. You do not need a response spectrum loading for doing that.
(Please visit the site to view this file)