Sorry you'd a rude shock.
I've been Stage IV with liver met from the get-go but opted for mastectomy as I just wanted the tumour to be out of my body. The psychological effects did me wonders as I've enjoyed the last 4 years being NED following surgery. This might be something to consider if you're bothered by the skin mets.
I'm also a believer of tumour load reduction. I feel that surgery can help to get rid of the visible BC cells (on the scans), thus leaving the body coping better with on-going chemo to kill off any remnant BC cells.
I'm no doctor so ultimately it really depends on what options you're comfortable with.
Regarding Stage 3 or 4, I feel it's just technical term. I'd a friend who was diagnosed with Stage III BC but didn't live beyond 2 years. I was all prepared to go in 6-12 months time but I'm still here 4.5 years with liver met. I think Herceptin has given us ladies a life-line. Let's try to enjoy whatever time we have with our loved ones to the fullest!