Stupid DVD burner questions for a newbie


I have had my mac mini for a couple of months now and love it, however I didn't purchase it with a superdrive. I know you can upgrade one yourself or get a store to do it, but I was thinking of getting an external unit to save the hastle.
My questions are:
Do I need any extra software to use one or are they natively supported by the os x (Tigger) All I want to do is copy data it and maybe an ISO image?

Anyone have any recommendations for a cheap one (in the UK) not bothered about dual layer.

many thanks