How many weeks gestation is the typical ectopic when it is diagnosed?

Depends. But usually around 6 weeks or so. As the fetus grows in the fallopian tube, it will get too big for the tube to stretch and cause pain. Occasionally bleeding can occur. The pain is usually what leads to the diagnosis.
It Depends. A hormone level lets doctors know how far along the pregnancy is, and whether or not they can see anything using ultrasound. If too small to be seen, your doctor can follow these hormone levels to make sure they rise correctly. A growing fetus located in an abnormal site can cause pain & abnormal bleeding, which red flags. If you have these symptoms, please see your doctor.