My mum had a lumpectomy, she did have the needle biopsy on her lump and it turned out to be nasty the fastest growing cancer you can get, (not sure on the gradings, i think grade 4) but fortunately for her they caught it relatively early and it hadn't spread. She was in for 3/4nights, she was put under a General anaesthetic they removed the lump and some of the lymph nodes surrounding, just to be safe. She had a drain in for her stay in hospital and she produced quite a lot of gunk and stuff hence why she was in for so long.
She did then undergo pretty strong chemotherapy and radiotherapy but has now been clear since 2009, although she still has meds to take for another couple of years.
I would suggest that you have the needle biopsy done first so they know what it is, unless there will be a pathologist in the theatre at the time of the lumpectomy to assess what the lump is, otherwise you may have to return for further surgery, thats if they have to wait for the results to come back to them (what i am having to do on a different tumour - if you happened to read the thyroid cancer thread).
Try not to worry about what it could be, i know how hard that is but everything at this stage is purely speculation, if its this then it could mean this, and this could mean this....the list is endless and if you are anything like me you get worked up into thinking the worst of the worst.
Definitely educate yourself on the possibilities but just so you can ask the right questions.
Sorry for rambling so much, but i think you need to find out whether a pathologist will be in theatre at the time of surgery so that really can be your decider on which route to take......
x