Modifying nouns with question phrases

Question

The sentence at hand:

サンタクロースをいつまで信じていたかなんて事はたわいもない世間話にもならないくらいのどうでもいいような話だが、・・・

I assume なんて here serves a derogatory role as など does in the following sentence:

あの人の言ったことなど気にする事はありません。

As far as I know, the particle can be removed without significantly changing the meaning of the sentence completely or making it ungrammatical.

However, if we remove the particle from the first sentence, we have the following noun phrase.

サンタクロースをいつまで信じていたか事

As this is the first time seeing a question modifying a noun, this looks rather odd to me. I would have probably inserted a という or って in between.

1. Is this a common construct? Can questions modify nouns other than こと?

2. Would it also be correct to insert という or って in there? If so, how would the meaning change?

3. Perhaps this getting is off topic, but are my observations regarding なんて・など accurate?

Answer 1

サンタクロースをいつまで信じていたか事

Your intuition is correct, this phrase is ungrammatical. You must insert という or って (サンタクロースをいつまで信じていたかということ).

According to a dictionary:

３ ある事物を例示して、次の語と同格であることを示す。…などという。「田中―人、知らない」「人間―ものはちっぽけなもんです」

So when なんて directly modifies a noun, you'd have to think of it as など + という. （田中など人 or 人間などもの are also ungrammatical)