Casual questions. When making questions using the casual form you do not generally use "か”, the question is generally understood by the inflection used in the sentence, much like English. Women sometimes use the "の” at the end of the sentence to sound a bit more feminine, however it can come of very motherly since it's and explanatory の. "で” as a particle is used to denote the location at which you completed an action；Example: I drank coffee at Starbucks while reading a book. 「私はスタバでコーヒーを飲みながら、本を読んでいる。」 Also onomatopoeias are used sometimes in Japanese, some like "waku waku" can seem a bit childish, or cutesy, others are not. It's best to learn the context and how they are used before including them in vocabulary.