I'm just trying to confirm that all paying Adobe customers are able to use Data Warehouse Requests.
Is there a detailed feature matrix somewhere which specifies what features are available on which tiers?
Yes, you can compare the Analytics Packages here: https://www.adobe.com/analytics/compare-adobe-analytics-packages.html
Generally Data Warehouse is available, but you need to have an Admin give you access to the tool.
However, SFTP isn't the easiest to get working with Data Warehouse; FTP and email are the out of the box most supported methods of delivery. Hope this helps!