I'm not sure how to say "I want to talk to you about many things", is 「/Name/に話したいものがたくさんある」okay?
Your attempt is already good, but you have to use こと instead of もの because a topic of a conversation is not tangible.
I want to talk to you about many things.
あなたに たくさんの ことで 話をしたい。
There are many things I want to tell you.
あなたに 話したい ことが たくさん あります。
depends on who/relationship but, I would just say something like ; いろいろを話したいな。or いろいろを話し合いたいですね。