I think in restrictive societies a larger percentage of the population uses prostitutes than compared to more open ones but that's just my hypothesis.
Quite wrong, prostitues are used more where their availability is more. Thailand is world's hub for people who want to buy sex. There are millions of women from countries from nearby countries who come there to work, same in Hong Kong. Similarly UK which does not prohibit prostitution attracts lots of asian and european women.
Secondly, buyers of prostitues are regular guys, young men in 20's and 30's.
THIRDLY, buyers usually do it away from their area of residence and job. These men do not hire prostitues of their own area rather they travel to different countries to engage in such activities.