If it's a true mirror you still have only one root partition and remving the kernels with the above command should have removed them from the system....
That is only rules for the forward chain. If you need port forwarding refer to the DNAT rule example I wrote above. But in that case it wouldn't have...
It's almost impossible for software to damage your hardware. It might only look like that if a piece of hardware fails when installing some software....
I don't recall the exact resize options in Disk Management but if it allows you to shrink the logical partition only (without shrinking the extended...