There was a brick building built for the standard gauge line in the late 60s, I think it went in the early 2000s, but don’t quote me on that. A building of identical design survives today at Yunta, and the one at Jamestown was also of this design.
As for platforms I’m not really too sure, places such as Yongala and Jamestown had a short concrete platform with a lock up shed adjacent to the main line. This was added for the standard gauge line, but I have no idea whether Crystal Brook was ever blessed with one.
As mentioned in a previous post, all the stations on the line other than Peterborough and Pt Pirie were at ground level.