> nas-1.8nb1.tgz                673547  x 84    56577948

This is terrible. (And it has happened to me before also.) pkg_add should 
keep track that it already retrieved this one time. An easy way would be 
to put all the extracted packages under one tmp directory using the 
package name as the sub-directory name. Then check that. And don't delete 
the temp directories until pkg_add is finished.

> I'd better send a problem report.
> Should it go to 'pkg' or 'port-i386' do you think?

"pkg"

Yes, please submit this.