Free tools for converting the maps as needed:

Converting to Kml format
Online tools for converting ShapeFiles to KML format: My Geo Data or Map Data

Converting to other formats
Online tool for converting ShapeFiles to Topojson, geojson, svg and png format. And much more: Map Starter

Reducing File Size
Online tool for simplifing and reducing ShapeFile: Map Shaper

DBF Editor
For Viewing and editing dbf files: DBF Plus

GIS Editor
For viewing and editing shp files: Open Jump