Quote Quoting c_j_mcginn
If I sell it to the interested party does the tenant have 30 days to vacate the premises or do I or new owner have to evict the tenant?
If you don't evict the tenant, and the new owner wishes to end the tenancy, the new owner would have to evict the tenant.

Quote Quoting c_j_mcginn
If I send a notice to the tenant will it still work for the new owner or will he have to redo it all?
If you wish to give notice and be sure that the new owner would be able to evict based upon that notice, that's something you should work out with the real estate lawyer who handles the transaction.