Yes you are probably right guess the rock is only basalt that...

Yes you are probably right guess the rock is only basalt that can get away with a 47 degree pit angle in fresh rock , pits only go down around 180 meters in depth so like you say "shellow" , just a little deeper than a dunny drop .

You can look at the July 23 feasibility study to get an idea of the metrics ,guessing table 32 may give one an idea of strip ratio

I have taken all the costs as valid , just find their cost per BCM surprisingly low , probably a reason why their ming cost is so low , and their strip ratio looks high but I have no professional experience to make a judgement .