What happened to the Yeshiva of Shem v'Aiver and all who learnt there?
They died. Yosef carried what they taught on.
Differing shitas on what they learnt, but because they lived through the evil generation of the flood, they had better haskafa on living with evil than the rest. So they say they taught the laws of chutz la aretz there, that Yakov only needed once he fled from Israel.
They also taught Torah which was outside of Olam Hazeh opposite to what Avraham taught a Torah that was connected to this world. That is why Yaakov needed to spend 14 years there before spending 14 years at the House of lavan.
When Yaakov had his dream, he dreamt of the ladder which as the posuk says was rooted on earth and touched the heavens, i.e. it tied together both schools of thought.