you can dig any rock out of the ground
yes there is rock under all the ground if you dig you will get to a layer of rock which is very hard to dig through.
It depending on how hard the ground is. If it is really hard he will only dig small holes in the ground, but I doubt he will dig a barrow.
The future tense of dig is "will dig" e.g. "He will dig a hole in the ground tomorrow."
For transportation. It is also the best place to dig them.
If there is no wire in the bottom they certainly can and will dig out.
dig into the ground
dig it out
No
Dig him out of the ground.
They wont dig very deep, but they can burrow underneath and escape if the fence isn't deep enough into the ground.
Yes, they dig burrows with their powerful front claws.