Ask about costs and a clear explanation of the alternative paths, public and private.
A clear explanation of how your case and team is run. A clear explanation of each step, eg once your tumour is removed, the treatment may change as it may be bigger than shown on a mammogram. Who is the point person, how your GP can help you with allied health. Which leads into...
Ask about access to counselling should you or your family want to have any. How do you access it. Referrals, recommendations, available services in your area. Same with a dietician if required.
Ask if you have to decide now. It moves so fast at the start and we can be rushed into action.
If there is not one present or offered, ask about access to a breast care nurse, and how that relationship functions.
Ask for copies of all you test results, pathology etc. You may not want or understand them now, but you almost certainly will later.
That's all I can think of now. It's not pleasant to think back to that time!