For frequently changing data hourly up to 24, daily up to 7, weekly upto 4, monthly up to 12.
For daily changing data daily up to 7 and etc. as above.
For seldom changing data a backup every 3 days with rotation based on a storage quota, and retention of manually held samples.
Did you read it to the end?
Without root user login, the attacker would have to guess not only the password to the user but also the username (hopefully it’s not something simple like admin), and once you are logged in you can use sudo -i to chage into root, which will require a password, therefore, we also disable password login so if someone does manage to somehow compromise the SSH user, they’d still need the password to become root.
You could spin a publicly exposed WireGuard daemon firewalled to allow peers access to the non-public SSH port only, which would result in double encryption, but would give you the peace of mind that an attacker would have to compromise both at the same time, which is very unlikely. Plus, WireGuard is very cheap to deploy and produces no logs. We use that model in my office to access our server.
Edit: Otherwise, as others mentioned, you’d move the SSH daemon to a random port, disable password login and weaker keys and cyphers, setup Fail2ban, and optionally setup GeoIP blocking (only allow IPs from your region to connect).
Either use a dynamic DNS service, as many others have mentioned and probably easiest, or, assuming you only want yourself to have access to the services, another option is to use something like Tailscale or a WireGuard/FRP instance in a static VPS as the rendezvous point.
I was flat out rejected by my ISP to have a static IP, though I only had it changed once since I started hosting services, so ahatever.
The way a reverse proxy works is to literally stand in the middle of a connection, so either side only sees them communicating with the proxy, oblivious to the actual endpoint. The only “solution” to this, though it’s more of a hack really, is to somehow send the original IP as additional data in a way that both sides agree on, e.g. the X-Forwarded-For header as others have mentioned, however, as I’ve said, both sides need to support and aggree with that, so you may have to find a setting/config to enable on the services behind the proxy. Think of it this way, if services blindly trusted that header and you weren’t using a reverse proxy, a bad actor could send a request to your service with that header included thereby spoofing their identity in your logs, therefore, this kind of thing is usually opt-in
As for the hardware: