What is the meaning of "Avudah" as opposed to 'Avodah'?
Rashi: 'Avodah' means work (one job); "Avudah Rabah" is many enterprises.
Seforno: "Avudah" means land that is ready to cultivate.
Malbim: It is agriculture. 1
Malbim: Normally, one person cannot succeed in both agriculture, which requires staying in one location, as well as raising animals, which obligates going to new places to graze. Yitzchak's success was miraculous.
Why does the Torah not mention silver and gold, as it does regarding Avraham (see Bereishis 13:2)?
Ramban: Because it was regarding sheep and cattle and thriving enterprises that Yitzchak outshone Avimelech, and that is what they were jealous of, and not of his money.
Why did the Pelishtim 'cut their noses to spite their faces' by destroying the wells which they could have put to good use?
Oznayim la'Torah: Many a factory and business was destroyed by the Jew-haters throughout the generations causing a loss to their own country and kingdom - simply because they belonged to Jews, for which they always found an excuse - as was the case here, as Rashi explains. 1
What is meant by, "va'Yekan'u Oso Pelishtim"?
Targum Onkelos: The Pelishtim envied him.
Ha'amek Davar: If it meant envy, it should have said 'va'Yekan'u Bo'! Rather, they pained him, like in Melachim I 14:22.