What is the proper procedure when one passes the Miqat unknowingly, and how is the intention for Umrah made, whether as Tamattu' leading to Hajj or as Umrah only, before visiting Medina? Is it permissible to postpone the farewell circumambulation (Tawaf Al-Wada') and perform multiple 'Umrahs before intending for Hajj? And what is the ruling on collecting pebbles from Muzdalifah and departing after the farewell circumambulation?

Assuming ihram from the miqat or parallel to it is obligatory for Hajj and Umrah. Whoever passes it without assuming ihram must either return or offer a sacrifice (dam). If you intend to go to Medina then return to Mecca, you can assume ihram for Umrah first, then for Hajj from Mecca (tamattu'). The dam for tamattu' is waived according to the Hanbalis and Shafi'is for one who travels a distance allowing for the shortening of prayers outside Mecca, then returns for Hajj. The farewell circumambulation (tawaf al-wada') for Umrah is desirable (mustahabb), but for Hajj it is obligatory and can be delayed until the time of departure. Buying goods after tawaf is not prohibited if it does not take a long time. It is sunnah to perform much tawaf in Mecca if it does not cause hardship. Staying overnight in Muzdalifah is obligatory, and it is permissible to depart from there after midnight.