Writing: give her time to day dream. Give her opportunities (without pushing) to talk about/ draw/ make animations of what she imagines. Encourage her to watch lots of good stories (films, TV shows, whatever) and to read lots of gripping books. Give her notebooks, access to wordpad, whatever. Give positive but also constructive feedback when asked for it.
Vocabulary: when she asks you what a word means, tell her, or look it up together. That's it, isn't it? That's how my children's vocabulary expands. There is a whole genre of cartoons really aimed at adults but that children can get a lot out of (like Garfield, Calvin and Hobbes, Peanuts, that sort of thing). We have a huge number of "what does this word mean?" conversations coming out of those kinds of books.
NB my children are home educated, so they do have time, lack of comparison with peers, and adults around who can be responsive pretty instantly (what with not being responsible for 30 children at once), so it's quite easy for these things to develop organically. I have no idea how one would be best to support development of those skills with a child who was spending hours of time and expending huge mental energy in school every day.