The out of the box approach in ArcGIS is to set up a template, and import that before you start adding dataset-specific metadata.
Importing metadata with different geoprocessing tools—Help | ArcGIS for Desktop
If you have existing metadata you want to update certain fields (say all the metadata for datasets in a folder), XSLT transformations can be developed. This is fairly complicated, but if you have 200 datasets with incorrect phone numbers, this beats editing them by hand! (Aleta Vienneau nice work on this article, it is very practical and helpful!)
Editing metadata for many ArcGIS items—Help | ArcGIS for Desktop
UPDATE: I should add that you can save contact information to your app profile as part of the ArcGIS metadata editor so you don't need to re-enter it every time. See the info on this help doc about the "Contacts Manager."
Editing metadata—Help | ArcGIS for Desktop
