Were the shops and local conveniences (pubs, bars etc) company owned & run or contacted out to other companies? How free was a private business able to establish a means of supplying services to those who lived and worked in the town?
The downside is that when BHP closes the site (temporarily or permenantly, as is happening now), the primary workforce is moved out and the secondary businesses (school/shops/cafes) become unfeasible - not a good place to build a long term business!
Are you paid in cash, or in company scrip?
I would be very surprised to hear that people were paid in anything other than cash, though wages would have taken into consideration that accommodation and food was free (as it does with all on site mine workers).
Mine workers in Australia are paid very well in comparison to a lot of other industries so a debt cycle mentioned by others probably didn't apply as much.