It’s new so I’m new

Hi everyone,
I’ve been diagnosed with DCIS on October 3rd. Left side.
By my next appointment on the 22nd I’m supposed to decide on whether to have a lumpectomy or mastectomy. 
And then surgery is meant to happen on the 31st.
Was anyone else’s doctor this quick in action? 
I feel like it’s such a short amount of time to try to learn as much as possible to make an informed decision.
He also said that I could get an implant, but that’s a whole other thing to think about too. 
Is a silicone implant covered by Medicare?
If I wanted to have a double mastectomy by my own choice, would Medicare cover that as well? (And an implant on that second breast too)
I’ve got about a thousand questions running through my head at any time.
Thanks for reading.