I would combine the three procedures and do them all at once. While you have her knocked out for the spay, have your vet do the lumpectomy (or mastectomy) at the same time. This will save recovery time and will prevent further tumor growth. It will also save some money.
Our policy in rescue is that we spay every dog before adoption. We have spayed 10 and 12 year olds with no problems. And we did a full mastectomy on a cocker at the same time as her spay and it worked out really well. She lived another 5 years and did of old age, rather than mammary cancer.
Let me know if you still have questions.