I'm going to try and get in touch with some groups that can do everything in-house from architecture to design to construction.

From an architecture/urban planning perspective, I think this would be great.

Hire a designer in the beginning of the project to make architectural changes that they believe will add aesthetically, such as moving light fixtures, changes to kitchen cabinets, shower niches, etc.

Architectural plans were recently completed.

Or is there another metric to calculate this price without have architectural drawings.

Below is some references for your use.Fair Housing rights are controlled by the Fair Housing Act, the ADA (see above) and Section 504 of the Rehabilitation Act of 1973, with a few provisions in the Architectural Barriers Act.

What are the benifits of a design and build firm with an architectural design element in house? 

Apply to the zoning commission with architectural renderings.

Anyone has a ball park estimate of the cost and lead time necessary to get plans (engineering+architecture) and obtain permit for a 700 sqft ADU ?

-Anyhow here are the costs:Dirt-80kSurveys etc (boundary, tree, topography)-1kConstruction budget hard costs-230k"Oh sh**" budget-10kBuilder Fees, Architectural Plans, Architectural Consult Through Project- 35kTotal all in: $356,000Projected sales price: $435k (conservative).