1. How can I set up the queue for loading and unloading plugins queue according to my list (for example, plugin C should be loaded first of plugin A, etc.)?

2. How to save the world (map.sav) when unloading a plugin and restarting the server, so that it can be saved before shutdown?

I think you can do "//Requires <MyPlugin>" at the top of your plugin with the using statements which will make the plugin wait for the required plugins to load before it loads itself.

You could prob just run the command "server.save" in the server console.

when server shutdown, the world does not have time to be saved and the necessary functions are performed.

void OnServerShutdown()
{
Interface.Oxide.DataFileSystem.WriteObject(Name, storedData);
Server.Command("server.save");
Puts("World Saved");
}

with the hook "Unload" is the same.