Answer 1

There are quite a few actually.
I suppose any language that can capture audio convert into a file that can be parsed into data that can then be compared to a sample could be used.
The actual process is far more complicated than I have expressed. I think the best for this would be c++ due to its speed. Python maybe. Speach control is easier to achieve than actual recognition of a particular person's voice. 8bit computers from the 80's had this capability if you had certain hardware connected to them.
Nowadays it can be done with any kind of device with the right software.