Woodster is exactly right. The CCC does not prohibit the exchange of money for sex services. What is does sanction is as the man says: "communication for the purposes of". The confusion creeps in because LE usually uses the communication about the fee involved as the grounds to arrest on this charge, not the simple discussion of whether a guy wants sex, and what the lady is willing to provide, although they will use this if the john is a little slow or reluctant to talk money.
The other ones are "living off the avails"- primarily aimed at pimps or possibly madams, and "keeping a common bawdy house". The later is very rare, and strictly speaking does not apply only to sex. There's a very famous case about a guy renting a hotel room for a high stakes card game (don't remember offhand if it was for poker or otherwise). The organizer was charged with the bawdy house provision.
Some SPs justify outcall only as a means to prevent being charged under the "bawdy house" provision. As long as it's consenual sex between 2 adults, very unlikely that any charges would be laid with regard to this provision.
Advice to boyfriends living with SPs: theoretically you can be charged with living off the avails....
The main point of all this of course is that generally speaking, as long as neighbours aren't complaining, LE would rather the trading of the money, the discussion of services, and the act itself be behind closed doors. Thus, unless you are in a MP that is open past curfew, it's unlikely you'll ever run into the "bawdy house" provisions.
As for "study" of the issues, I once had a prof who had bookshelves of materials on prostitution in Canada and elsewhere, many of which were written or edited by him; a "life's work", if you will. I don't think there needs to be any further study. The government needs to legalize it, have it moved indoors in safe, regulated places, and provide regular testing and other healthcare services for the workers and customers. If this means a surcharge on the "going rate" in order to ensure and pay for "safe" sex (not just in terms of disease), then so be it....