We had our own priest and singer, so we only needed to book a pianist through the church. However, the masses we attended there always had a great priest and featured great singers, so anyone needing those services from the church should be in good hands.
Our wedding day ended up being the hottest of the year, so far. Unfortunately, the air conditioning was not set to a level strong enough to cool down the church. If you are planning a summer wedding, I would consider the heat factor and make a note to ask the church about a standard AC level. I wish we had anticipated that.