Hi Michelle,
Those are the standard terms provided to all Discourse installs by default. You are welcome to change them as you see fit for your community, including removing that line. We recommend consulting with a lawyer to develop terms that fit your community.
Assuming you host your own site, we - Civilized Discourse Construction Kit, Inc., the company that develops Discourse - have no access to your data.
We have no access to any data on your site, unless such data is already public (and thus anyone on the internet has access to said data).
We do not track content on your forum. It is up to you to ensure the health and safety of your community. The only data we regularly collect about sites we do not host is their URL and installed Discourse version. We collect this data when your site pings us to check for new update. Both the URL and version of your site are public information, we have no special access that allows us to obtain it. If your site was behind a firewall (off the internet), we would not even know it exists.
100% correct. There are no ad features as part of Discourse core, so there is nothing to disable. You’d need to install Discourse Advertising Plugin (Ads) or a similar plugin in order to have ads.
If we host your site, we clearly have access to all of your data. See Discourse Standard Hosting Terms | Discourse - Civilized Discussion for the terms that govern our usage of hosted customer data. (Spoiler alert, we don’t scrape our customer sites for advertising data, sell their data, or anything else nefarious)
Hope this clears things up! Let me know if you have any further questions.