Create Master Contacts List in Google Contacts from Multiple Spreadsheet Lists

We are looking to create one master contact database in Google Contacts. (I'm open to suggestions if you have a recommendation. We are not interested in Salesforce.) In addition to basic contact information(name, company, address, email and phone), we want each contact(where possible) to be assigned to a group(s) for use in marketing. We have 30-40 Excel files in various formats(mostly csv and xls, xlsx) containing contact lists that need to be formatted for upload to Google Contacts. Some of the lists contain categories or groups. These also need to be standardized and formatted within the spreadsheet so that they will show up as Groups in Google Contacts. Once all lists are uploaded to Google Contacts, merge duplicates. Delete the dated groups created with each spreadsheet import. The entire database then needs to be uploaded to our Constant Contact account in a format that coordinates with Constant Contact. We will occasionally need to refresh the Google Contacts database with new contact lists. Please provide a blank spreadsheet formatted with the proper columns for importing to Google. Please also provide a blank spreadsheet and/or written description of how to successfully export from Google Contacts and upload into Constant Contact in order to refresh the database in Constant Contact. Once the work is agreed upon, I will provide you with a link to an Evernote note and or share an Evernote Notebook where we can collaborate if needed. We can use Google docs also, but I prefer Evernote.