! Just a couple of points,
There is no timing chain on the R53. I am assuming he means the supercharger belt, get him/her to send you a copy of the service booklet.
Why would they have had the power steering pump replaced if there wasn't a problem? It is an expensive part to get replaced just for the sake of it. ~$2000 The reason I ask is that if it has failed, then it can be because of something or cause other things. Get this cleared up.
I would ask get pictures of the insides of the doors, they are very easy to scratch and can look tatty, can't see from the pictures.
It has a sun roof, ask about this, as they can have some problems and there is no fix other than replacing the whole sunroof, it is one complete part.
Get pictures of the alloys, they can be fairly easy to replace, but can be another cost, they look pretty kerbed from what I can see.
Also ask about the windscreen, MINI's a prone to stone chips and it may mean a new one to get past the rego testing when you get it re registered in Vic.
Also get pictures from under the door seals, they can hold a bit of water there and sometimes have rust.
Finally ask for engine pictures and if it has ever had any oil leaks, the engine mounts/bushes can go if they are the old type. Usually the first thing you notice is a oil leak on the left of the engine bay. The other thing in the engine is the coolant expansion tank can leak if it hasn't been replaced with a updated one. (gold tank at the back of the engine bay right of centre).
Not trying to put you off here, but you are looking at a 9 year old car. They are pretty reliable cars if well looked after, the engines are usually pretty bomb proof. Check all those things and you should be pretty right!
* I may or may not know what I am talking about and my advice must not be taken as gospel!