ところ vs どころ: Interchangeable or different meanings altogether?

Question

I have two questions.

A) Why do they use どころ instead of ところ in this sentence? Is it possible to use ところ without changing the meaning?

写真では建物と池の風景だけで静かな雰囲気を味わうことができますが、実際に行くと、観光客が大勢いて、金閣寺の美しさを楽しむどころではありません。

B) Is it correct to say the following?

金閣寺の美しさを楽しむ(なんて)とんでもない。

Answer 1

As you imply, どころ indeed seems to have been derived from ところ by rendaku, but today, it has evolved into an independent expression. It is no longer part of a compound. The initial voicedness stands by itself. You cannot replace どころ with ところ any more.

金閣寺の美しさを楽しむどころではない
'It goes without saying that you cannot enjoy the beauty of Kinkakuji'.

金閣寺の美しさを楽しむところではない
'This is not a place/moment where you are supposed to enjoy the beauty of Kinkakuji'.

Interesting question. I had not realized cases where rendaku fossilized into an independent expression.

The alternative you give is correct. A related expression with a different meaning you may want to compare with is:

金閣寺の美しさを楽しんでいる場合ではない