For a 5mm intraductal breast cancer with 1mm of invasion, taken at lumpectomy and then a mastectomy performed, how many lymphs should be removed?

It depends. The current standard is to perform a sentinel lymph node biopsy; if (+), additional nodes are removed (unless radiation therapy planned, which would not be the case with this minimal tumor). The median number of sentinel nodes people have are 2-3, however some have 1, others can have many more--this does not reflect the tumor but rather the way the breast drains towards the armpit.