We recommend that you arm yourself with a Plan Check List from your city building department before you begin hiring drafters, designers, engineers and architects.
Since requirements can vary widely in different communities, professionals bidding on your project may not know which plans and services are mandatory. If you lack information, some of them may charge for services they are not qualified to perform or that are unnecessary.
A little research up front can save you time and money. You will know who to hire and what plans & documents you will need to submit for permitting.
Here is a typical TI Improvement Check List from a city in Orange County, CA. It specifies the type of plans to include in your permit plan set submittal + information that must be shown on each plan. Send a Plan Check List to each design professional who you invite to bid on your project.