What is the grammatical form of "v'Karav"?
Radak: It is a command; it is Dagush 1 . There is a Patach under the Reish, like "Katar Li" (Iyov 36:2), "Palag Leshonam" (Tehilim 55:10).
I.e. there should be a Dagesh in the Reish. However, Reish does not receive a Dagesh; in place of this, there is a Kamatz under the Kuf. (PF, based on Minchas Shai.)
What do we learn from "Lecha l'Etz Echad"?
Radak: After writing on each one a name by itself, bring them next to each other in your hand, as if they are one.
Malbim: He holds them as one.
How will they be "la'Achadim b'Yadecha"?
Rashi: I will fuse them to be one stick in your hand.
Radak: The two will be in your hand for one ? for a sign that Malchus Yisrael will be one.
