1)
What does 'Pituchei Chosam" mean?
1.
Rashi (citing Targum Onkelos) and Targum Yonasan: It means that the letters were (not written, but) engraved 1 on the stones. 2
2.
Sotah, 48b: They wrote on the stones with ink and held the Shamir worm 3 above them
2)
What does the Torah mean when it writes "Musabos Mishb'tzos Zahav"?
2.
Ramban: It means that the stones were surrounded by prongs. 2