Some of the immediate questions might be around your lumpectomy surgery, when it is, where will the incision be, information about your recovery like how long you will be in hospital and off work.... Final decisions about treatment may not be made until they get the pathology from your lumpectomy. Ask for a copy of the report, ask about any restrictions that you may need to consider and the process around your treatment - many hospitals have a specific process around how treatment decisions are made.
Thats a start - you are bound to think of more....
all the best for your appointment
Chris