Better than the hardware, certainly. But advances in surveying technology make new surveys worthwhile, occasionally, so the data does have a lifespan. Of course better analysis techniques or more powerful hardware for old data makes a big difference too.
Yes, although it's not usually a case of doing the same thing with new tech and getting better results. You'd have to have some hint that oil might be there from the first survey.
But my experience is mostly not-seismic, so I'm not sure how the survey parameters would be adjusted for a revisit.