Translate this?

what this excatly means? what is moshiyokereba?

お部屋の移動がありますがもしよければお部屋をお取りします。

空室状況は日々変わりますのでお早目の返信をお待ちしてます

Apparently it's from hotel/inn, correct?

"moshi yokereba" is "if it's OK with you," "if this suits you."

お部屋の 移動が ありますが もし よければ お部屋を お取りします。
You will need to move rooms, but it this is Ok with you, we'll reserve the room(s) for you.

空室状況は 日々 変わりますのでお早目の 返信を お待ちしてます
Room availability constantly changes (on a daily basis) so I await your early reply.

btw, does anyone know, what means kusomiso? I think it is something dirty?

Reply to someone's question.

kuso means shit and miso means japanese bean paste.
kusomiso in one word would traditionally mean messing up one thing and another,
but today some people would be reminded of a title of homosexual manga (comic), "kusomiso technique".