Do send interview questions at least a week before the interview. The day before is no good.
Do get the spelling and pronounciation of your guest's name correct before you start recording
Both excellent points. I remember interviewing Nicholas Petreley from Linux Journal one day and my best guess at the pronounciation of his last name was off. I asked him before we turned on the recorder, though, so nothing was lost.
For some reason I had never considered sending my interview questions to my interviewee. It makes perfect sense, but completely escaped me. Have to add that to my list.
As Leesa intimates, your goal should be to make your guest sound like the most knowledgeable and sophisticated person on the planet. If you're successful, your guest will be more likely to promote the show and be available for you again, and your show will also gain by having such great guests.