Call back after 3D Mammo (not my first 3d mammo)

Hello all:

I have had mammograms every year-18 months for the past 12 years (I'm 52). Had a 3D Mammo last year, results were clear.

Had another 3D Mammo this year (2 weeks ago) and got a call back. Scheduled for "additional imaging" next week.

Just pulled report down the my doctor's app. Under findings it says:

"Comparison: Prior examinations dating back to 2007

Technique: Mammography Screening Bilateral with Tomosynthesis

Findings: Left The breast is almost entirely fatty. There is a mass seen in the inner central region of the left breast.

Right The breast is almost entirely fatty. There are no suspicious masses, calcifications, or areas of architectural distortion."

So, I am thinking the following (please tell me if I'm wrong in my interpretation):

The fact that I had a 3D mammo last year and it was all clear, and now this year's 3D mammo shows something means something has changed.

The radiologist has "ruled-out" this being a calcification or architectural distortion.

This is a "suspicious mass".

Questions:

1. What does "inner central region" mean?

2. I don't see a BIRADS anywhere - when/how do I get this?

3. Any idea what "additional imaging" I should expect? They told me it could take up to 3 hours. Ultrasound? Another 3D Mammo? MRI?

4. They wouldn't be planning a biopsy and not tell me would they?

5. If they confirm the presence of something suspicious, could they do a biopsy "on the spot" or would it be scheduled separately?

Thank you!