Why does the Torah write that Yaakov took "the stone... "? In 28:11, it says that he took "stones" (in plural)?
Rashi: They had fused into one. Refer to 28:11:8.*
What is the difference between a Mizbe'ach and a Matzevah?
Ramban #1: Whereas the former is made of many stones, the latter comprises just one stone.
Ramban #2: Whereas one brings Korbanos on the former, on the latter one pours wine or oil. 1
Matzevos became forbidden when they entered Eretz Yisrael and Mizbechos permitted, because the latter were not as popular as Matzevos among the idolaters, or because the Torah did not want to prohibit everything.
Why did Yaakov pour oil on top of the Matzevah?
Rashi (to 31:13), Rashbam and Seforno: To initiate it for use upon his return journey (twenty years later). 1
Malbim: The rock symbolized unity. Pouring oil on it symbolized that via unity (of Yisrael), they will merit Shemen Mishchas Kodesh (a Supreme influence).
Why did Yaakov not pour wine on the Matzevah, like he did on his return journey (35:14)?
From where did Yaakov get oil? Elifaz took all his money, and Yaakov left Eretz Yisrael with only a staff (Bereishis 32:11)!
Tosfos ha'Shalem (1, from Pirkei d'R. Eliezer 35): "Es" teaches that oil descended for him from Shamayim.
Pane'ach Raza: The staff was hollow and full of oil, so Yaakov could light it and learn at night. 1
Even if he could make a fire from sticks or rocks, where did he get a lamp? Also, there were no Sefarim at the time. Why did he need light in order to learn? (PF)
How could Yaakov make a Mizbe'ach from a stone that a person used? This is forbidden (Zevachim 116b)!
Tosfos ha'Shalem (4): One may make a Bamah from what a person used.
Perhaps one may make a Matzevah 1 from what a person used. (PF)
It seems that the Griz (Menachos 22a), who forbids also a Bamah from what a person used, must say so. (PF)
Why does it say that Yaakov rose early?
Ha'amek Davar: It is a time of acceptance of Tefilah and Korban. He vowed to Hashem amidst Tefilas Shacharis.