1st . i want to ask regarding long vocal and the addition of ---
when do we add vocal or use dash ( --- ) in words, for example for grandmother we spell おばあさん with additional あ . whereas cookie, we spell it クッキー with addition ー . but both are pronouce a bit long on obaasan and kukki~ so when to use additional vocal or - ?
2nd . i want to ask regarding the な adj. only apply hiragana な if the adj is not end with い ?? but for the sentence a job is important ( しごと は たいせつ です ) doesnt apply な