Amud 119b

However, before it, there is a Mitzvoh to bless - אבל לפניו מצוה לברך

Summary:
אביי seemingly does not coincide with a previous תוספות that יהללוך is the conclusion of the ברכה ראשונה of הלל.

Rav said; that they should not move from group to group - אמר רב שלא יעקרו מחבורה לחבורה

Summary:
One may not eat elsewhere after the ק"פ, but may do so after eating מצה.