custom firmwares... yes.. they allow you to play backups basically... but you'll need a modchip which void your warranty and you can't play on live unless you have a way to disable it ( sonicsam has his haxed, he knows more about this)
as for the wireless, you'll need to buy an adapter which allows you to connect to the network... has to be designed for the xbox... bear in mind that if the signal is weak it might lag a bit