Under fsaverage/surf there is both an lh.white and an lh.white_avg file, while under average/surf there's only lh.white_avg. I repeated the mri_surf2surf command above with "--s fsaverage" instead of "--s average" (since I understand in this case it's the same thing), and then it ran to completion.
It should be close but probably not exact.

So if I want to use the study-specific "average" subject surface with mri_surf2surf, rather than the generic "fsaverage" one, how can this be done given that the required ls.white file only exists in the latter but not in the former? Can I just rename (or duplicate) ls.white into ls.white_avg?

Also,

1) Doesn't mri_surf2surf also need to be applied to surface of individual study subjects, or only to the (fs)average subject?

2) Shouldn't the input to mri_glmfit be the output of mri_surf2surf? In the group tutorial, the former is "lh.gender_age.thickness.10.mgh" while the latter is "lh.gender_age.thickness.10B.mgh". Or should it just be the unsmoothed output of mris_preproc?

3) Assuming the label files (corresponding to my ROI, and extracted from the Destrieux atlas) are different for each subject, and given mri_glmfit is called just once, for all subjects, which label file (corresponding to what subject) should I point it to?

Thanks!