It's unstated at this point I think. I don't think it was answered even in Magic Kaito Public baths in Japan are still used, so I assume there is a higher cultural tolerance for seeing other unrelated people naked. Shinchi and Ran went to visit with the Kudo parents in LA and then Yukiko got musical tickets so she had them fly to new York directly after that. It isn't weird to fly overseas without adults at their ages anyway, especially if they are going to meet up with more parents at their destination. Judging by Shinichi's house, his family is probably rich enough to afford it. As for Hattori and Kazuha, a quick scope of fares for flights and bullet trains between Tokyo and Osaka look to be about 10000-13000 yen. That's not that bad, and I doubt their families are hurting for cash either. They probably also visit to go shopping and things, so it's not totally just to harass Conan and Ran. See his wiki page. It has all the known info about his family in it. Assuming you mean Itakura's program, I have a theory on that. Three years previous, Itakura stopped developing CG due to poor eyesight. Two years ago Tequila showed up at his office to say he didn’t need him anymore. One year later, he was later forced to develop a program with a year deadline. He didn’t want to complete the program “for the sake of humanity.” (380)Itakura’s program is something an ordinary person would program; specifically someone who programmed games. It probably was a personal project of Itakura's as he was able to stop developing it on a whim; something he wouldn't be able to do so easily if he was paid to make it. If it is a personal project, it doesn't have to be specifically related to games. It could be something related to game development like artificial intelligence, networking, modeling, rendering, etc, or it could be something completely different. That the BO could find out about it in the first place probably indicates that Itakura didn't keep it secret. That means it probably not a virus or something highly illegal Itakura would not want to speak of, although modified it may have those applications.
I suppose it's a matter of spin the dials to try out voices and see what matches. The system must be pretty intuitive because Conan somehow can quickly match voices on the fly.