What is the significance of the Berachah that Hashem blessed Yitzchak?
Rashi #1: He came to comfort him upon the death of his father.
Rashi #2 (from Bereishis Rabah 61:6): He blessed him with the mandate that He had bestowed upon Avraham, to bless whomever he wished. 1
Sotah, 14a: This teaches us that it is a Midah of Hakadosh-Baruch-Hu to comfort mourners.
Malbim: As long as Avraham was alive, he was primary in the house, and all dealings were in his name and were blessed due to his Brachah. After he died, Yitzchak entered in place of him, and he needed a special Brachah.
Ha'Emek Davar: Hashem gave him success in everything. It was not a verbal Brachah.
Rashi: Because Avraham was afraid to do so, since that would have included Eisav (whom Avraham foresaw would go off the path) - so he left it up to the Master of Berachos to do as He saw fit. (Below (verse 39), Rashi writes that Avraham died early, lest he see Esav go out to evil ways, which is not 'Seivah Tovah"! Perhaps he merely saw potential that Esav sour. Or, he saw that he would sour, but not how much. Or, seeing in actuality is far more painful than seeing through Ru'ach ha'Kodesh.
Why does the Torah inform us that Yitzchak lived by the well of Lachai Ro'i?
Ramban #1: It was a famous well, so the Torah tells us that it was in the area of that well that he lived.
Ramban #2: Because he lived in an uninhabited area, the Torah needs to tell us the nearest known spot.
Malbim: In Avraham's lifetime, Yitzchak used to go there to pray. After Avraham died, he settled near that Kadosh place.