Contact Database and management to produce Mail Merge

We have built a business database in the form of many csv files covering the United Kingdom. This contact information is important and needs to be housed properly so it can be accessed and worked with. We need a database and intuitive front-end to manage the data to improve it's quality, add and update fields, merge duplicates and create groups of contacts based on multiple search terms that we can add to a group. Typical problems arise such as duplicates, being able to merge and build better single entries are key. The data needs to be searchable with multiple terms being added to the 'basket' to produce an export list for Mail Merge. Ability to browse files easily but require an edit button submission so data cannot be accidentally changed. Data fields: Company Name Address Address 2 Address 3 Town County Postcode Region Country Contact Full Name Contact Job Title Email Address Phone Number Fax Number SIC Code NAICS Code Business Category Web Address Business registration Number VAT Number Notes section We need to be able to upload the .csv files and tell the program which column relates to which field. Almost all files are laid out the same, but we'd like to ensure no data is corrupted in upload. Ability to upload data where an address field may have a comma without corrupting the upload. Export lists for mail merge and check boxes for what is to be included/excluded from export. Smart export of data as some fields with short addresses may have county and region as the same eg: 'Durham' and 'Durham'. If we export this to map it on Google, the record will read the name twice. Suggestions sought.. Duplicates, compare entries and merge fields, add new or drop. Aim is to have one contact with good information not several with partial even if one contact includes several names, emails and phone numbers. UK Counties are often shortened, need to replace Bucks. with Buckinghamshire, Lincs. with Lincolnshire Herts. with Hertfordshire etc. Search and sortable for export by creating groups based on partial name/keywords (recyc rather than recycling and recyclers), SIC code and more. Need to create campaigns by searching and selecting multiple category fields and adding them to a group that we can name. One entry can belong to multiple groups. For example, a plastics recycling facility may get grouped by us as part of a campaign under 'machinery', 'recycling', 'Waste handlers', three groups we can create and export as separate groups.