It was the major center of Hellenistic learning. In particular, the scribes and others responsible for the reproduction of the manuscripts were well trained in Greek. Utter, absolute, nonsense. Most of those who transmitted the manuscripts made this claim. These numbers are the purest fantasy.
Syrian tradition is something of an oxymoron.
It is certainly true that examples of both of these classes of errors exist in the manuscripts. However, it is simply false to say that either type of error was the exclusive province of either tradition. Every book and article on Textual Criticism of the NT that I have at hand discusses this point. It is interesting to note the logic in the above. No modern translator would even consider using the Wescott and Hort NT collation as his underlying Greek text.