Why Hyde Park become Haido Park?
I'll be basing my answer off the anime adaption of these chapters, which took place in episode 425. 

There were three possible victims this time, all of them were candidates for the House of Representatives in Japan. This number is based off the fact that there would be three interviews. The letters "DJ" were overheard as the target and the place they overheard for this murder was "Eddie P." 

When Haibara is asked what Eddie P is she states that P means that it is a park.

Later, Conan gets a call from Ran and answers in his normal Conan facade. Jodie notices this and calls him out on it saying that he has a double personality:


This triggers Conan to think about the following clues:


Hunting Ground
History
Park
Double Personality


Besides history, which is just something Vermouth mentioned as this is an old story, these clues are all elements of the Jekyll &amp; Hyde story; from these clues Conan remembers the scene of Mouri Kogoro flipping through the Jekyll &amp; Hyde book.

The closest you can transliterate Jekyll &amp; Hyde in Japanese Katakana is ジキルとハイド. ハイド can be wrote in Romaji as Haido (it's also the way it is pronounced). From here Conan concludes that it must be Haido park and they manage to get there before the camera crew.