Did members of nobility pay rent to live at Louis XIV's court? Did they pay for food or was everything provided for?
Also, I read that during the reign of Louis XIV, Versailles was open to the public - even the apartments (and bedrooms) of royalty. Wouldn't this have posed a huge security threat in terms of potential assassination attempts, as well as theft?
They were provided for. Versailles was a golden prison. But everyone did not stay at court everyday. Many of the wealthiest nobles had an hotel somewhere close ( like in the city of Versailles ) where they retreated after the day at court. There the hotel was theirs (bought or rented ) and when they organized festivities or hold their " own little court " it was up to them to pay of course.
Plus, many nobles, those who were not the political elite ( ministers, secretary of state, ...Etc ) would live for several months every year to live in their castles or manors, generally in the countryside.
Servants were also provided for, and there were a lot of them. Meaning that being a servant at Versailles, or generally for the King's court, was an excellent advancement in life.
You read right that Versailles was extremely open. This is due to several thing. First the King was a public person so this, a access to Versailles, was wanted by the monarch. But it does not mean that because one could walk through Versailles and see the King. The second reason is practical, Versailles was constantly being built. Thus, workers and artisans needed to get from a point to another to do their work. Yet, there has been foreign witnesses who were surprised at how easy it was to walk in Versailles, even visiting the chambre du roi ( the public King's bedroom ) without being bothered by a guard.
As for the security, the King was rarely alone, especially Louis XIV. But security improved during the affair of the poisons. On the other hand the openness of where the monarch lived became troublesome during the reign of Louis XV, when Damiens almost killed him. This was not new to Versailles however. When Henri III was murdered by the monk Jacques Clémentin 1589, the murderer managed to get to the king without being bothered by anyone ( the fact that he was a monk played a part ).
As for theft, I don't know if there have been any studies about it, or if there even is any kind of sources we could use.
Sources :
Versailles: Au Service du Roi by Mathieu da Vinha ( which I am very sad it has not been translated, it would be a success even among general public. Anyone working in book editing ?? ).