וכסף משנה, to use for purchases.

אולי משגה הוא, perhaps the money had been placed in one of the fodder bags to help the official identify to whom the bag belonged, and when he filled it with grain he had forgotten to remove the cash.

כאשר שכולתי שכלתי, an expression parallel to Esther’s saying when she risked her life appearing uninvited before the king, saying: כאשר אבדתי אבדתי, “if I have forfeited my life, so be it.” (Esther 4,16)

וידברו אליו פתח הבית, before they entered the palace.

ואלוקי אביכם, it was public knowledge that the brothers were well trained in miracles, matters metaphysical.

ויכינו את המנחה, while the produce had been wrapped in the sacks on the way, it had suffered somewhat, and the brothers now tried to restore these items to the appearance of freshness.

It would be spitting and a shame for the Egyptians to eat with the people from across the river [ever hanahar], since those people were contemptible in their eyes, and the Egyptians were haughty, as it is written (Isa. 30:7), "I call this, 'They are a threat that has ceased.'" Similarly (Gen. 46:34), "For all shepherds are abhorrent to Egyptians" -- they despised shepherds because sheep were contemptible in their eyes, as it is written (Exod. 8:22), "If we sacrifice that which is untouchable to the Egyptians before their very eyes, will they not stone us!" That which is repulsive to the Egyptians and disgusting, if we sacrifice it before their eyes to our Rock, won't they despise us, stoning us in a shaming way, as we find (II Sam. 15:5-6), "Shim'i ben Geira came out from there, hurling insults as he came. He threw stones" He cursed David and stoned with dirt, in a shaming way.

וישבו לפניו, Joseph had given instructions to arrange the seating order in order of their birth.

ויתמהו, they were utterly amazed, seeing that they had all been born within a space of seven years and they could not understand how their ages had become known to Joseph.

ותרב, as if the Torah had written ותרבה. The meaning is that Binyamin’s gift from Joseph was far greater than the gift received by his brothers. A parallel construction to the word vaterev appears in connection with the construction of the Tabernacle ותכל, vatechel, where it means that the construction had been completed (Exodus 39,32).