Personally I have found it awkward to ask especially if it is a first visit. I still get a little nervous my first time meeting someone for that very reason. I dont know what they like, and I know some guys might be uncomfortable to discuss details during the actual session as well.
I know I would like to know beforehand if the guy I am with expects 2 or more pops in an hour so I can bring you to an exploding orgasm in the first part of the session to allow more recovery time for the second. In MY ideal session this would be DATY time!!

So fill out your p411 completely guys (that is what it is there for) and personally, I do not find wrong with an email introduction. It would in fact make me more at ease and knowledgeable as to what to expect.