Create a CSV file dump/feed whenever item of Content Type A is created
Look at Views Data Export. It can create a CSV from Node content.

It sounds like you need this to somehow be recurring over time ... this is a tall order and so I wont be providing much code, but will outline a possible solution:


Implement hook_cron_queue_info(). This is a cron task that runs off of a custom Queue. You can insert a NID every time a node is created into a custom queue you've created named MyCSVQueue. Every time a node is created it gets added to this queue -- when you process the queue you create individual csv files.
Use either hook_node_insert or Rules to place the NID into the work queue.
In your queue worker function you pass the NID to a custom view that uses a contextual filter to load the NID. Or, you may be able to use node_export to create the CSV data as well. You then simply use the Drupal File API and file_save() to store the csv file somewhere in your public/private drupal filesystem.


If the default Cron options of drupal dont suite your needs look at Ultimate Cron

EDIT

A slightly easier alternative:

Use:


Use either hook_node_insert or Rules to run a snippet of custom PHP code. Simply create a file directory using the File API in public files as: %files/csv_node_exports/MM-DD-YYYY. Your snippet can create the directory if it doesnt exist today yet.
then just export the node data to a CSV file. You may or may not have a NID yet ... you could always update the filename after the fact to reflect the actual NID assigned to the node.