Other times the top conducts a negotiation interview covering these topics shortly before playing. It is also common for the bottom to initiate the conversation by bringing up these questions. It is a general term covering all manner of topics that the prospective partners typically want to clear up in advance of getting started in a scene so that they don't have to disrupt their play with conversation that is not quite in the mood of the scene. But most people find it works best to get some things straight in advance.
Many people find engaging in negotiations to be very hot preliminaries before play.
Often the bottom really enjoys being invited to talk so intimately, and the top often enjoys listening and getting ideas. Further discussion usually ensues. Negotiation is most often a form of flirtation and verbal foreplay, although the result of it is an agreement that also serves as a formal contract between the partners. I ask whatever subset of these questions I think might apply to whatever I am considering doing. If I skip something that suddenly becomes a possibility mid-scene, I either don't do it or I ask about it quietly and unobtrusively.