Hi,

Do we need to input in Lumped Masses and Snubber in Modal analysis or only in control parameters.

What to check in output reports of modal analysis Natural frequency report?

You almost never need to use the "lumped mass" dialog. This is there mostly for "academic" reasons.

You may need snubbers, but that depends on the specific job.

If you run a modal analysis, the only results to check would be the natural frequencies. If you want to see what the individual mode shapes look like, use the "Animation" module.