1)
What is the meaning of "Bachur va'Tov"?
1.
Radak citing Targum Yonasan: He had good form and appearance.
2.
Malbim: Even though he was young, and the boiling of his blood had not ceased, he was good with Hashem and people, and was not drawn after his lusts.
2)
Why does it say that no one from Bnei Yisrael was better than him?
1.
Malbim: Also among older people, no one had better Midos.