「日本に行く」「日本へ行く」 both are right. In this case both 「に」 and 「へ」 mean "to" in the sentence of "I go to Japan" To translate "I'll stay here", we can say 「わたしは ここ に います」, but not 「わたしは ここ へ います」 because 「へ」 can be used only when the sentence refers to a direction of movement. So the verb "stay" does not have any movement in direction. If we describe "He will come here" can say both 「かれは ここ に 来ます」 and 「かれは ここ へ 来ます」 Do you see the difference between this and 「わたしは ここ に います」? By the way 「三しゅう間の　りょうこう　の　しました。」 is not correct. We don't say 「りょこう ”の” する」. The right way to say "travel" is 「りょこう を する」, 「りょこう に いく」 「りょこう へ いく」 Good luck for your studying.

"What, what do you wanna say?" in Kansai-ben

"Understood?" in Kansai-ben

To tell you the truth Konnichiwa is pretty formal. We don't usually say that to someone who's very close like friends. Here are the example of "Hi" in Japanese. But I have to say that they're all sort of manlike. やあ (yah) よう (Yō) よっ（Yo） おっす (oss) ちぃっす (chi-ss) Hope it helps you a bit. Good luck =)

both sounds improper. 私には兄と姉がいます。 is the right way to say that. Also... 「うちには犬がいます。」 = 「私は犬を飼っています。」 = I have a dog.

「～る＋ともり」 is not correct. Remember, always use つもり. 「つもり」 means "with an idea of oneself as ～" or "have a mind of ～" First, 「死んだつもりになって、働きます」 We could guess that he is right in the middle of a job interview. In literal translation, "I'll work hard with idea of myself as dead" or "I'll work with a mind to die". Almost same meaning as "I'll work hard like there's no tomorrow". 「コーヒーを飲んだつもりになって、貯金します。」 He wants to save up some money as he stops buying cans of coffee. So literally "I'll save some money as I have a mind that I already had some coffee." 「何かに使ったつもりで貯金した。」 "I saved some money with a mind that I bought something" Also we can say: 「明日の午後には出発する'つもり'です。」- I'm 'planning to' leave here tomorrow afternoon. 「あなたはどうする'つもり'ですか？」 - What 'will' you do? 「やってみる'つもり'です。」 - I am 'going to' try to do it. 「あれは冗談の'つもり'でした。」 - That was 'meant as' a joke = I was 'going to' make a joke 「これは何？」「卵焼きの'つもり'。」 "What's this?" "It's 'supposed to be' a rolled egg..." Hope it helps you. Good luck!