1)
What is the difference between "ba'Chutz" and "ba'Rchovos"?
1.
Malbim (here and 5:16): Chutz is in back of the houses. Only the household is found there. Rechov is the wide place in front of the houses - there is Reshus ha'Rabim. It is full of people.
2)
How does she ambush in every corner?
1.
Malbim: She traps (entices) people who go on the side (like verse 13 explains).