Do you mean lawn seed area? if so - I put fine grass cuttings on my thin/bald areas and it works for me. But if you have seeded a lawn area already wait and see if you need to? If its any other seeded area then no as some grass/weeds may germinate.

Not sure what you mean - if you mean grass clippings from cutting the grass with a mower, what would be the purpose of spreading them over lawn seed? They'll block the light and decompose. If you mean cuttings (and I can't believe you do) in the sense of rooted plantlets, then fine.