NO
You need a internet connection on your Xbox to download games on the marketplace. You could use ethernet but you can also use wifi (wireless).
No, you do not need wi-fi.
Yes, a person can download games on the Xbox with Wi-Fi. This is done by using points to purchase games through the Xbox store. Internet use is required.
If you want to connect to a Minecraft server on the PC you will need some sort of internet connection to connect to the server. On the Xbox, you will need internet,as well as a Gold Subscription, to invite others to your map or join someone else's map On mobile devices, you must connect them both to the same WiFi network to play together on a world
You don't. If you have the new Xbox 360, you don't need a wireless adapter because it has built in wifi. But if you have any other Xbox 360 console then you will need a wireless adapter.
You need pay only for the adapter. If you have a wireless router you will not have to pay to anybody for your WiFi. But you still have to for Internet.
You need to download an emulator that supports wifi
Yes you need internet to play online multiplayer
no
no you dont but you do need it to download the games from the app store.
No you need wifi. 3G would not have enough bandwidth.
It really depends in some cases. If on the Xbox 360, no. But if you get it from Origin or steam you will not need wifi.