Limestone pavers can vary in porosity and surface texture. Clean Image of Orlando recommends to have it sealed for this reason. Depending on customer goals and current conditions, we would recommend either an impregnating sealer or Seal N Lock sealer.
The green staining in the pictures is common with homes with copper gutters. The removal of the stains requires a special stain removal process. We have visited this home 1 year later and no more stains have appeared. The sealing is doing its job.