devtrackers.gg
Yes, especially when you host your world on it.
Yes, especially when you host your world on it.
How often/much does the host save to or read from disk?
You can set the save frequency for the savegame in the configs, by default it's a minute. The database is written to continously, the more players, the more often. Pretty much every second. That's how databases works and why you cannot just 'kill' the game, that leading to a corrupted database. Big queries are cached and saved in specific non-changeable intervals.
Writing every second is going to be rough on an SSD, but fine for a leased one.
I've seen the caching of several queries in action, but it would make a lot more sense for the ones that I've noticed to be cached client-side as well, with the same cache expiration- it's going to cause the server the same order of magnitude of seek time to pull the cache from disk as to run a query from disk. and the same amount of I/O overhead to transmit it to the client.
That's no problem for current NVMe SSDs, and I personally use Datacenter ones for servers.