What are the files and fields in CiviCRM?
Sounds like you're new to CiviCRM - Welcome to the community. Here's a link to the CiviCRM data architecture page on the CiviCRM wiki.

You can create multiple custom fields in CiviCRM so you should be able create the fields you need for your existing data. During import you can choose which fields get imported and which CiviCRM field they get mapped to. 

For match/merge of duplicate records - see: Deduping and Merging

For capabilities of selecting subsets of contact files based on things like member type, zip code, has email address (or not) - see: Searching and Groups &amp; tags

I've mentioned import already - there there various way to export data, including Exporting Contacts

You should try out the demo(s) or better still, download it and create a sandbox to explore CiviCRM's functionality.