Dennis, your guess is accurate. The "Cntrl Rm/Phones" output has a separate volume control from the "Mains" out. However, this won't solve your problem; it is the same mix going to both places. To effectively create a useful monitor mix, whether for in-ears or floor wedges, you need two completely independent mixes, one for the house and one for the monitors. What an artist needs to hear to perform optimally is virtually always different from the appropriate mix to best present the performance to the audience (congregation). Even in a simple setup like yours, I would bet that the track/vocal balance the singer wanted for monitoring would be significantly different from the best possible house mix. To try to use the same mix for both house and monitors is a recipe for disappointment on the part of the artist and the congregation alike. Artists who aren't hearing what they need in the monitors aren't comfortable and rarely perform well. Also, you could not make adjustments during the performance (if necessary) without changing the monitor mix, something else the performer would find very distracting. If we are talking about multiple singers, either during different parts of the service or on different days, the problems only become worse and more complicated. I realize the 802 has a very attractive price and that budget concerns can be significant in small churches, but I really don't think it will do the job you need. In that case, inexpensive or not, it is money wasted. I spent over 30 years as a professional sound mixer, for top popular musicians and Broadway musicals. I would not have tried to do what you seek to do with the Xenyx 802. Quite frankly, I can't really think of an application for which I would find it appropriate. There is just not enough functionality there.
Greg
P.S. Well, I stand corrected, at least a little bit. As I was wrapping up, it did occur to me that the Xenyx 802 might be adequate for either a lobby or backstage "Page and/or Program" system where no monitoring capability was needed.