I will continue with some of what @Frank Chin said as an Architect.

I'm sure you'll also need an architect and engineer for the scope of work you have planned.

I know some attorneys and architects who specialize in getting zoning approvals and then selling to builders.    

I had several discussions with framers and architects by could not come into a conclusion on what is the best.

Do I need to hire an architect?

Typically you'll need to have any architect draw up the plans to prove that you are meeting the required square footage's, dimensions, etc by code. 

Which required architects, contractors, Foreman.

The next post will show you how to research what you can actually build once you know what zone your site is in.Zoning is one of the more obscure aspects of the development process, but in our experience, once you acquire significant strategic knowledge and create practices around this research and identification process, the value and marginal utility to be generated can be very significant.You can hire an architect to do this zoning research for you, but as a developer a big part of your "value add" is to identify strategically what areas have the zoning that you need, or where you found a site and the zoning works for what you want to build.

If you do need an owner rep my first suggestion would be to approach the architect who did the design and see what their fees are for doing this.

Yes consult the entire design team, architect, structural, civil.