typo
思います
So which is proper in this context? このように or こんなに?
1)
このように indeed means "like this", but it's not the same as こんなに. こんなに implies "excessiveness".
2) 3) 4)
Yes.
Is the following correct? It is intended to mean "private education, in a word, became a double-edged sword and".
原動力になって
私教育が韓国の発展の原動力になり、私教育は一言で「両刃の剣」のようです。 sounds awkward. なり is inappropriate to connect those two clauses.