My main question is to the employment status of prostitutes in the old west working at saloons or brothels. Were they simply bought and sold from one madame/saloonkeeper to another (such as what the Mann Act targets) or was there a portion of prostitutes who could move freely from one location to another and choose where they worked? Did they make their own money and give a cut to the saloon keeper/madame in exchange for room and board or were they more like contract workers? Finally, how much control did the saloon keeper/madame have over a prostitute in their every day life, especially concerning their ability to switch jobs (choose a different occupation or simply choose a different place but remain a prostitute).
I would love to hear what insight /u/itsallfolklore has.
First, the West covers a great deal of territory and whatever the "West" means spans many decades, so arriving at generalities is problematic. In general, the West could be an extraordinary free place: the women who found themselves engaging in sexual commerce may have had circumstances that hemmed in their choices, but they were usually free to leave for another community and strike out in any direction they wished. An exception to this would be Chinese-American women who often arrived in what amounted to slavery, and so their ability to chart their own courses could be terribly limited. I will leave the plight of Chinese-American prostitutes for others to address.
For the others, employment and employment options could be extremely fluid. It was, needless to say, a rough life. One received better protection in a brothel, but one had to pay for that protection in the form of sharing proceeds. Independent contractors frequently worked out of "cribs" - the one or two-room cottages in the red light district that served as home and place of business. Some did - as you indicate - work out of saloons, but this was often a matter of working outside the law, since communities frequently established the red light district through ordinances, restricting prostitution to only that area, and yet most saloons were outside that district.
In Virginia City, Nevada, the focus of my research, there were prostitutes operating out of the notorious Barbary Coast, particularly after the red light district burned during the Great Fire of October 26, 1875. With the rebuilding of the red light district, city officials worked to relocate prostitution to the designated area, but many lingered in the Barbary Coast, working out of back rooms of saloons. Community officials spent several years attempting to have prostitutes leave the area, and they were ultimately successful.
Anne Butler, Daughters of Joy, Sisters of Misery (1987) remains a classic work on the region's prostitution.
Let me know if you have any questions or if I was not clear here.
I need to add - particularly given your user name - that Anne Butler found that Irish immigrants made up a disproportionate number of the prostitutes in the American West. Nineteenth-century Irish women tended to immigrate in numbers equal to the men, and they often arrived single. These statistical traits made them unusual among immigrant women, and so this may have been a factor in how they filled the ranks of prostitutes in the West.
On the other hand, I found next to no Irish prostitutes in Virginia City, a fact that I discussed with Anne (who was a delightful person and a wonderful historian). We speculated that the absence of Irish prostitutes on the Comstock might have been due to the influence of the imposing Father Manogue, who ruled the spiritual half of Virginia City with an iron fist - and an imposing 6'3" frame! Anne and I wondered if it was simply the case that he would force any Irish woman out of the ranks of the fallen in an act of saving them and their souls. There are accounts of Manogue performing similar acts of interference, so it is not impossible to imagine such a thing.