for fMRI, those files with a 1400 or 645 in their names are multiband data. those files with 2500 in their names are common acquisition protocol data.

About DTI bvecs and bvals,

1) If you downloaded NIFTI format data, you should have them in the same folder with the dti.nii.gz.
2) If you download Dicoms, please use dcm2nii program to get  bvecs and bvals. http://www.mccauslandcenter.sc.edu/mricr...