Yes. Continue to #8.
No. A developmental editor doesn’t focus on spelling, punctuation, grammar, or style, but rather on consistency and pacing of the story, and may recommend restructuring or leaving out content. A developmental editor may assist at early stages of turning an idea or outline into a draft or once the manuscript is complete.
If you plan to publish your book through a traditional publisher, you may consider skipping this step, but be prepared for your manuscript to be rejected or to go through heavy editing by the publisher’s chosen editor in that case. See Why You Need an Editor and Stages of Editing from the San Diego Professional Editors Network.
Continue to #8.