It depends. Depents on the size of the breast. Whether or not an axillary node surgery such as sentinel node biopsy and/or axillary node dissection is being done and also the type of reconstruction. Usually muscle flaps take longer than implants. So based on the circumstances it may take somewhere from 3 to 5 or 6 hours. But please realize that the time of surgery is very unpredictable.
Type reconstruction? A double mastectomy usually takes about 3-4 hours. If implants are used for the reconstruction, this takes another 2 hours. If a free tram flap is used, then plan on an additional 4-6 hours in the operating room. Generally the reconstruction takes longer than the mastectomy.
Varies. Are you looking for a surgical time, or are you looking for a time from start to finish? There are multiple reconstructive alternatives which take anywhere from 1 hour additional to 10 hours additional in the operating room. Usually the entire procedure can take upwards of 1 year to fully heal and sometimes longer.
Depends on why. Usually the beginning of the reconstructive process can take place at the time of mastectomy. If radiation will be needed, many plastic surgeons will recommend delaying reconstruction for about 6 months.