File preview service

Hello. A question regarding the file preview service.

In the Terms of Services it states:

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11. Joomunited file preview service

Joomunited provides a file preview generation service using its own servers. This service is provided for free and may be restricted or canceled at any time in case of abusive usage at Joomunited's convenience.
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My questions:

1. Is it possible to turn off the file preview per-category?
2. I have confidential files on my server. Does JoomUnited keep a preview of the file after generating or is it discarded afterwards?
3. Can I host my own file preview service?

Thanks in advance!