1)
Does the verse literally refer to another man's wife?
1.
Rashi: Yes. However, we can also expound it to discuss idolatry - it is not for you.
2.
Malbim: Yes. Bi'ah with her is like drawing coals in his garment.
2)
Why does it add "Lo Yanenakeh Kol ha'Noge'a Bah"?
1.
Malbim: Even if he does not lie with her, only he touches her, his feet will be scalded, like the Mashal of walking on coals.