Bus transportation from Amman to Karak

it is called Raghdan Station in Mahatta Str.

It is difficult to explain as I don't know where you live. It is not in downtown as you know the area as downtown but it is close to it.

If you take a taxi the driver knows how to get there. The bus will leave as there is enough passengers so the waiting time  depends on this. You don't have to make a reservation at forehand. But it is wise to call the office and ask for information about departure time,  frequency etc.