It is really the CEO's job to prepare RFPs, but that is generally not feasible. RFPs are so much work and take such a force of will to get done that it just makes more sense to pass them to an experienced professional. The CEO's time is worth a lot. But the CEO will still be directly involved, directly hiring the RFP Preparer, and providing anything else that is necessary, such as financial statements, resumes of the top management team, final approval of the bid amount, etc., etc. Every RFP has different requirements that they ask for.
Just a note that I have generally been successful with researching and finding competitive bid information. I can't promise that, but I am surprised myself that I have normally managed to find something when I have needed to. Also, I'm a big believer that the overall RFP represents the company, and really aim for a very clean and professional presentation. You can look at the samples I have included here to get the idea.
As far as payment, I take half up-front, mainly because I have to power the work. I wish I could do without that... but I can't. Doing an RFP properly is just a massive task, and it has to be powered. A thousand apologies.