> Is that correct to say that the effect survives correction for multiple
> comparisons using a small-volume correction procedure?

SVC is a little controversial, but if the anatomical structure (superior parietal lobe) is the only region of interest in your whole study, you might pass the reviewers' scrutiny when lucky.

> When you run a conjunction analysis, how do you determine the T-values of
> voxels in the conjunction region?

If you've already corrected for multiple comparisons for each individual component of the conjunction analysis, the corrected p of the conjunction would be the same as your individual corrected p (e.g., 0.05). This is a little conservative, but that's the best we can do.

> How do I extract and convert to nifti only that specific subbrick?

If the sub-brick number is 5, try

3dAFNItoNIFTI -prefix myOutput myInput+tlrc'[5]'

HTH,
Gang