Try to work out differences yourself before you go to the developer. He can also figure out how to minimize the impact of the disagreement on the manuscript. Keep in contact with your developer. Ask questions when you need to. But don't expect him to jump every time you call - he has a busy and hectic job.
Nothing looks less professional than a writer who turns in material with lots of misspelled words.
Don't try to become a professional writer unless you have a basic understanding of grammar. If it's been a long time since you took an English class, brush up. Buy a book on it. Don't abuse the customer. It's fine to have heated discussions with other roleplayers.