1) the brand depends on your budget. A good feature packed head unit which I found while upgrading my own music setup is the Pioneer DEh-4350..decent power output, ipod/iphone/usb/aux connectivity and other goodies..it also has 2 pre-outs for your planned sub and amp.
2) i suggest you buy your unit from one of the department stores like lulu/safari/carrefour and not from the car shops here..there's a big difference in prices between the two.