Unfortunately no guide, just things I've pieced together myself over the years.
Cloudflare is probably the easiest and most intuitive part of the setup though, you can setup dns/proxy/firewall rules very intuitively, and I'm sure there are plenty of guides out there.
Something simpler than some of the other self hosted drive apps (nextcloud and seafile) that I like is sftpgo
I have been thinking about this. For other sites it is super easy to google e.g. "bifl socks reddit" but with federated services the information is scattered across many domains/services that the search engines do not know are federated. There either needs to be a site that archives everything in real time that search engines can crawl, or a robust search engine specifically designed for searching posts on all known instances.
Full disclosure I am not an expert on the topic these are just my thoughts.
SUSE
Here is my setup:
Cloudflare fronts all of my webserver traffic, and I have firewall rules in Cloudflare.
Then I have an OPNsense firewall that blocks a list of suspicious ips that updates automatically, and only allows port 80/443 connections from Cloudflare's servers. The only other port I have open is for Wireguard to access all of my internal services. This does not go through Cloudflare obviously, and I use a different domain for my actual IP. I keep Vaultwarden internal for extra safety.
Next I run every internet facing service in k3s in a separate namespace. This namespace has its own traefik reverse proxy separate from my internal services. This is what port 80/443 forwards to. The namespace has network policies that prevent any egress traffic to my local network. Every container in the WAN facing namespace runs as a user with no login permission to the host. I am also picky about what storage I mount in them.
If you can get through that you deserve my data I think.