Is touching the Kaaba and pressing one's body against it, and placing one's hand on the upper threshold of the Kaaba's door, part of the Sunnah? What is the ruling on that? And is the imprint found on Maqam Ibrahim (Station of Abraham) indeed from Prophet Ibrahim, and what does it look like?

It is Sunnah to touch and kiss the Black Stone. If touching is difficult, one should point to it. For the Yemeni Corner, the Sunnah is only to touch it, without kissing or pointing. Both (the Black Stone and the Yemeni Corner) remove sins. It is also Sunnah to supplicate and stand at the Multazam (the area between the Black Stone and the Kaaba door), by placing one's face, chest, arms, and palms against it. As for Maqam Ibrahim, it is the stone upon which Ibrahim stood to build the Kaaba. It is Sunnah to pray two rak'ahs behind it after circumambulating the Kaaba. It is not Sunnah to wipe over it or circumambulate it, and it is not a grave for Ibrahim.