Why isn't ㅎ dropped in the word 퇴근하다? I thought that when certain consonants connect with ㅎ (ㄴ being one of them) that the ㅎ is dropped. Why isn't that rule applied to this word?

what's the difference between 그러네요 and 맞아요?

what's the difference between 네 and 그러네?

informal dialogs: この映画ねほんとに面白いし楽しいしいい作品だから！ どうして「ね」を「は」の代わりに使いますか。そうして「ほんと」は誤字ですか。 My working theory is that ほんと is an informal version of ほんとう and that ね can be used informally as the topic marker? Also, in the following dialog: 夏子：映画何時？ カゼ：８時４０分からかな。 What is からかな? I imagine から is "from," but ive seen the phrase からかな in informal Japanese before in a response where "from" doesn't fit, so im wondering if it's a set phrase.

そうですね I recently started learning a little bit of Korean, and the word 네 (ne) from my understanding is kind of like "yeah," or "okay", and it really stuck in my head because to me, it almost sounds like a shortening of the Japanese phrase そうですね, and I was wondering if informal Japanese ever uses this sort of shorthand. In English, for example, people used to use "ok" as shorthand for "okay" and that later became shortened to just "k" in very informal communication, like text messages. I feel like "ね" would be perfect informal shorthand for そうですね in Japanese under the right circumstances. Is this sort of thing done at all in informal Japanese, or even this particular example?

你嘅電話幾多號啊？ Hi all, In this sentence, "What's you're phone number" why is it 號 and not 號碼, and why is it coming after the 幾多 rather than between 電話 and 幾多? Is there a difference between this sentence and 你嘅電話號碼幾多啊？ Thank you!

我要可唔可以你嘅電話號碼 Hello all, In this sentence, which I'm understanding means, "can I have your phone number?" what is the 要 doing in that sentence. Would it not be the same without the 要? Thank you!

Am Samstag, werde ich auf der einer Geburtstagsparty sein. In this sentence, why does Geburtstagsparty get both a direct and indirect particle? Is the "der" here supposed to be the masculine nominative case, or the feminine dative case? I imagine it's the latter, as einer is strictly feminine. Also, am I correct in assuming the Geburtstagsparty is in the dative case because the speaker is will be "at" (auf) the party?

廁所 or 厠所? Are these too the same...I've seen both characters used (廁 with the dot on top and 厠 without the dot), but I'm not sure if it was just typo. Thank you!