Hi lena, Thank you for using BrainSuite.
1. The ROIs generated by BrainSuite are in the native coordinates of the subject. This is because BrainSuite and SVReg warp atlas to match the subject and transfer the ROIs from the atlas to subject.
2. It is possible to edit the ROIs generated by BrainSuite using the Painter tool
http://brainsuite.org/delineation/roi/label-painter-tool/
If you want to modify the atlas or draw your own ROIs and make your own atlas, you can do that using the custom atlas creation method:
http://brainsuite.org/processing/svreg/creating-custom-atlases/
BrainSuite should be able to process elderly adults.
3. The ROIs are stored as a separate volume in nifti file format. Most brain imaging softwares support nifti format.