All good advice above, most of the SPI (1994 - 1997ish) Coopers don't have the airbags etc, mine is a 95 and doesn't. They all rot like buggery sadly and everywhere. Mine looked mint when bought a year ago, has now got rot showing on both front wings and a panels, and a small hole underneath near rear subframe, also needs one sill doing! Defo make sure you get the mintest shell you can find. I would be inclined to get a cooper, if you want the big wheels then I would go for a spotspack or one with the arches done, the wheels look silly without the arches tbh.
They are not cheap cars to own and you will be forever working on them, but really good fun when they are working!

www.theminiforum.co.uk is a good place for info