You can say '漢字を書くのが難しいです。'
Other than the above, you can also say '漢字を書くのは難しいです。'
In these sentences, you need not say '私は'.
When you would like to say that I am better at reading Kanhi than writing,
you can say, '漢字を書くより読む方が得意です。'
As you think, using '方が’and 'より' work.
For your information, '読み物' /'書き物' can be used as noun and verb in Japanese sentence.
You can say '読み物をする'/'書き物をする’as verb and just '読み物'/'書き物' mean 'material to read' /'written document'.
I hope this answers your question.
If you have further questions, please feel free to ask me.