Don't Starve Together Server Hosting

Yes, and it is free. Log in to your Klei account, open the game servers page for Don't Starve Together, create a token and paste it into the panel. The server will not start without it, and it is written on every boot, so a corrected token takes effect after an ordinary restart.

Yes. The surface and the Caves run as two linked shards on the same server, and players move between them through sinkholes exactly as they would in a game hosted by a friend. That is also why plans start at 3 GB: you are running two worlds.

List the Workshop IDs in dedicated_server_mods_setup.lua, then enable and configure them in modoverrides.lua. That file exists once per shard, so keep the Master and Caves copies identical, otherwise a mod works above ground and not below.

By name. Don't Starve Together has no direct connect field, so players search for your cluster name under Browse Games. Pick something distinctive in the panel, and add a password in cluster.ini if the world is for your group only.

Survival, Endless and Wilderness are a panel setting. Season lengths, giants, resources and the rest live in worldgenoverride.lua for each shard. World generation settings only apply to a new world, so decide them before the first start or regenerate the world.

No, by default it pauses when the last player leaves, so nobody returns to a camp that starved in their absence. It is the pause_when_empty line in cluster.ini if you would rather let the days run.