1)
Why does the Torah insert "Yachanu" after "ha'Mishkan" by Gershon and Merari, and before it by K'has?
1.
Moshav Zekenim: Because Gershon and Merari had wagons to carry parts of the Mishkan; they encamped further from the Mishkan, and could ride to the Mishkan in the wagons.
