Why did Yosef tell them to hurry?
Seforno: So that his father should not continue to suffer (by being separated from him). 1
See Seforno to 45:13.
Why did Yosef say that his brothers should go up to his father, and that Yaakov should descend ("Redah") to him?
Rashi: Because Eretz Yisrael is higher than all other lands. 1
Hadar Zekenim: The Gematriya of "Redah" is 209, a hint to how long Bnei Yisrael would be in Egypt. Yaakov had said "Redu" (42:2), whose Gematriya is 210. A year passed in between. 2
Hence the Torah constantly talks about going down to Egypt (See for example, 39:1 and 42:2-3.)
This is astounding. It is only a four- or five-day journey (Midrash Tanchuma Miketz 6), and it seems that Yosef sent them back the next day! Perhaps Rosh Hashanah had passed (or Nisan 1, if the years are counted from Nisan). Yocheved was 130 when Moshe was born, he was 80 when he first came to Pharaoh, and the Makos took one year. We must say that Moshe had just started his 80th year, for after the Makos he was 40 years in the Midbar, and he lived to be 120, from day to day. If likewise Yocheved gave birth at the start of her 130th year, we can say that in all there were 209 years in Egypt! Or, Hadar Zekenim holds like Riva, that Yocheved was conceived on the descent to Egypt, i.e. the trip took over six months. Refer to 41:50:151:3 and the note there. - PF)
If Yosef wanted them to rush to inform his father, why didn't he send a message to his father before this?
Refer to 42:9:5.
Why must they tell Yaakov that Yosef rules over all of Egypt?
Malbim: It is one of six reasons why Yaakov should descend; Yosef could not leave Egypt to go to meet Yaakov. Also refer to 45:10:1:2 and 45:11:151:1.
Ha'amek Davar: Here, "Adon" is a master (unlike in 45:8). Yosef knew that Yaakov will want his sons to live apart, and not mix with the Egyptians. This is why he designated Goshen for Bnei Yisrael, and expelled those who were there initially; it is not from the primary settlement of Egypt. If Yosef were a mere ruler, he could not do so for his father and brothers. However, he is a master; he can do to his slaves as he desires, e.g. relocate them.
QUESTIONS ON RASHI
Rashi writes: "'Ascend to my father' - Eretz Yisrael is higher than all [other] lands." What does this mean; isn't the earth a sphere?
Maharal (Chidushei Agados Vol. 2, p. 147, to Kidushin 69a): Chazal mean that Eretz Yisrael is more holy than all other lands. That which is holy is highest (i.e. most significant); and as such, [conceptually] Eretz Yisrael must be positioned at the top of the globe. 1
Maharal (Be'er ha'Golah, Be'er #6 Ch. 13, p. 131): Eretz Yisrael is higher than all other lands, not in the physical sense, but in its essence. All other lands tilt towards the extremes, whereas Eretz Yisrael is the center, and contains everything.
