1)
The last four of these were not Shem's sons, rather, his grandsons (Bereishis 11:23)!
1.
'Rashi': They are listed among his sons for conciseness. Malbim - our verse means, and Bnei Aram were Utz v'Chul?
2)
Here it says Meshech. In Bereishis 11:23 it says Mash!
1.
'Rashi': These are close to each other. He was called by both names.
2.
Malbim: The Torah shortened his name to distinguish him from Meshech among Bnei Yefes (Bereishis 10:2).
