I remember watching this documentary where this guy infiltrated this british underground slave ring where they would bring in immigrants from other countries and force them into prositution and things. they filmed this man forcing a woman to give him head and she was crying and choking and then he punched her in the face and pushed her head into the toilet until she was almost unconscious. Things like this are the reason I personally think prostitution should be legal. The more illegal it becomes, the more it is forced into the shady underworld and the less protection these women can get. I've heard about places where it is legal where there are perfectly legitimate prostitution business, the women do it by choice, they get paid a very decent wage, they are protected and aren't forced to do things that they aren't comfortable doing. This shows to me that ideally the best way is to legalize it because it's a case of FRANKENSTEIN'S MONSTER. If you hide it away behind closed doors the problem is only going to get worse.
the problem is, though, if prostitution is legalized, a lot of the stuff you mentioned will not be allowed. inri posted a study about a brothel requiring condom use.
buuuuut unlike abortion, where if made illegal women will still seek them out and it becomes dangerous, many people do use prostitutes in order to fulfill some kind of shady sexual appetites. it can be something as mundane (but still unsafe) as not wearing a condom to donkey punches to rape fantasies and all sorts of shit. this isn't a small number of people either, most prostitutes encounter at least one john who threatens them and many are just raped. if you legalize prostitution, you don't necessarily remove the market for underground prostitution; it just becomes more underground.
legalization protects women to a degree, of course, and it keeps them from being thrown in fucking jail all the time for basically trying to survive. but it won't cut down on violence towards prostitutes; safe johns will meet safe women, but dangerous johns will meet women on the street who can't get into a ranch (let's not forget that in the US legalization does not mean nationalization so if you happen to be a black prostitute but they've already got three sorry sister not good for business) or who might have other things keeping them on the street (such as disease), and the problem will still exist and the whole sexual exploitation issue will be ignored in favor of pundits arguing about MONEY FOR SEX???