Also, if you're into geology at all, the flowstone stalagmites/ stalagtites are the most impressive I've seen in the peak.
I'm not sure about that flowstone. It's probably just calcium carbonate deposits (like limescale in a kettle) and not limestone, which would explain why it's so fragile.
No, it's the same process, it just occurs far quicker with concrete as the limestone content of the concrete is in much smaller granules, therefore has a higher surface area to allow it to dissolve more readily. As concrete also has a far higher permeability than limestone, there's far more potential to dissolve calcite quicker and reprecipitate it elsewhere quickly.