This is not an ending, they (the mangaka, editor, whoever) just decided to stop making new chapters. I can't see this as a completed work, there was way too much buildup toward arcs that just died on the vine. Really puts a hard ceiling on how well I'm able to see this manga from a quality...
That wasn't Adachi on the rope, it was Kanzaki. That comment at the end was just a joke, that of course Adachi was also caught doing something that evening
Yup, he goes in a set order of girls, starts with Kusuri, ends with Karane, and loops. The first compliment was for Kusuri, the last was for Karane, so each girl got the same amount.