What is the grammatical form of "he'Chacham"?
Ibn Ezra: The prefix Hei that introduces a question [usually] has under it a Patach with a Sheva. If the next vowel is a Sheva Na, the Hei has a Patach, like "habe'Machanim 1 " (Bamidbar 13:19). After Hei ha'Yedi'ah (to identify, like 'the'), the following letter has a Dagesh, unless it is Aleph, Hei, Vov or Yud; then, usually the Hei has a Kamatz, or sometimes a Patach. Here it has a Segol, to make the pronunciation easier, since the next two vowels are Kamatzim. It is pronounced just like "he'Chacham Einav b'Rosho" (14, even though there it is ha'Yedi'ah, and here it is a question.
Ibn Ezra: There is another case (an exception) in which it has a Patach - "ha'Yeitiv b'Einei Hashem" (Vayikra 10:19).
What will be the consequence of his son being a Chacham or Kesil?
Rashbam: If my son will be a Chacham, he will rule over it, and it will last in his hand. If he will be a Kesil, my toil and wealth will fall to others (Ri Kara - he will lose it via his folly).
Seforno: I hope to merit to leave my toil and acquisitions to a Chacham, so he will use them to perfect his intellectual Nefesh and acquire eternity, like Hashem's desire. If so, also I will merit that I helped him to do so.
Metzudas David: If he will be a Chacham, I need not be pained that my toil will pass to him. However, I do not know if this will occur!
Why does it say "Gam Zeh Hevel"?
Rashi: This is one of the Havalim created in the world, that a Chacham toils and a Kesil inherits him.
Rashbam: If my son will be a Kesil, my toil will leave his hand, and I toiled for nothing.
Rid: Also what I toiled for is Hevel.
Metzudas David: Gathering acquisitions to leave them for another to inherit after him, is Hevel.
