I stopped by the BrainVoyager booth and asked them about NIFTI to voi conversion, and it is a separate plugin that you can download. It's used for all NIFTI input and output conversion.
http://support.brainvoyager.com/available-tools/49-available-plugins/166-nifti-conversion-volumetric-files.html
Regarding the other question, you can use "3dTstat -min" . Most "3d" programs will work with 1D files too, but you will have to add a backwards quote to the end of the filename with a backslash too like this \`
