Did Isaac come off of the mountain with Abraham after the sacrifice of the ram?

The answer is logically "yes." Isaac is mentioned many times after the sacrifice recorded in Genesis 22, so he must have come down from the mountain. In addition, before climbing the mountain, Abraham made a promise. "And Abraham said to his young men, "Stay here with the donkey; the lad and I will go yonder and worship, and we will come back to you."" (Genesis 22:5). Notice the "we." Since only Abraham and Isaac went up the mountain, we conclude that Abraham intended that they would both come down at a later time. "So Abraham returned to his young men, and they rose and went together to Beersheba; and Abraham dwelt at Beersheba" (Genesis 22:19). Though Isaac is not mentioned, the implication is that he is with his father.

See also:

Questions and Answers regarding the Old Testament