the plain lead in "should" assist in not cross threading the fitting, however ive normally gone for the longer non lead in version personally,
2nd point i would believe that is correct,
However, as much as i like the idea of doing them in brass, £1+ each a fitting, f that, ill continue to use the plated fittings at 50 for £12, ive never had any issues with them corroding away like cackshifter is suggesting, either way each to there own