I had a stereotactic biopsy... mine was an out-patient procedure performed in the imaging facility where I had my mammogram. To detail it briefly, it whole process took a close to 3 hours... mostly due to paperwork and setting up the area for the biopsy. A local anesthetic was used. I was positioned face down on an examination table that had an opening in which the breast was suspend from. Then, a needle/ probe was inserted at the biopsy site. A sample of calcifications and breast tissue was then removed. I'm not sure if it'll happen in your case, but ordinarily, a titanium micro clip is inserted at the biopsy site as a marker for future diagnostic referencing.
Pain thresholds vary... and in my case, I didn't find the process to be particularly painful. Uncomfortable?... yes... with swelling, soreness and bruising. But, that goes away in the weeks that follow. Tylenol knocked out the little pain and discomfort that I did have... and ice packs worked wonders in reducing the swelling. I would estimate that it easily took 4-5 weeks to completely heal.
I was left with a tiny, barely noticeable puncture scar that now resembles a dimple. As for the pathology report, mine took a about 4 days until I was notified (thankfully, my results were benign). Anyway, results could be available sooner or take slightly longer than that.... depending on the lab workload and how timely the pathology findings are interpreted, completed and forwarded to your doctor.
I can relate to the nervousness... and I recommend that you maintain a positive attitude; try to relax; and have someone, like a close friend or relative accompany you to the procedure... moral/ emotional support is invaluable during times like this. Best wishes to you for a favorable outcome. Take care!
You might want to "search" the particular type of biopsy you are going to have to learn the entire procedure. As a rule it takes from 4 to 7 days to receive the Path. report on the biopsy findings. This of course depends on the day you have your procedure done and can also vary with each institution. Regards .....