Yes the unit will fit a mk5. Same plug on the back but a couple of pins need swapping if you've already got aux or a CD changer fitted.
You'll need to know the radio code too - probably have to ask the dealer for this.
Depending on the age of the mk5, you may need to change the canbus controller to prevent battery drain. Use the search function and you'll find plenty about canbus and whether it needs replacing.
