You can still do reverse domain lookups using the IP address as well as see the domain in the SNI details.
So the content is safe but the sites you visit are still exposed unlike with a vpn.
Although you would commonly find a long list of AWS or similar IP addresses which wouldn't be very useful, unless you simultaneously crawl tens of thousands of possible sites (from the same source IP range) to map IPs to sites.
No, though DNS-over-HTTPS is already basically a proxy.
By this definition, any DNS server is basically a proxy (assuming you are not hitting an authoritative name server for the domain you are trying to access).
No it isn’t. The DoH server is the final destination. It isn’t relaying your traffic to somewhere else.