It may be helpful to hire an architect or an AE firm to complete a feasibility study for you as a starting point to see if what you have in mind is practical and help you reach a ballpark budget. 

Do I need to submit plans from an architect/engineer or is City ok with owner-drawn plans?

@Jonathan Schwerin you may want to hire an architect to come up with a set of plans that you are happy with.

@Donovan Castaneda before looking at land, talk to some builders or architects who you'd be working with about the type of building you'd like to build.  

I design all of my own buildings utilizing Chief Architect software.

It would also help increase income for homeowners/landlords and increase work for builders and architects.

As the project scope increased I hired Architect.

I need an architect and an expediter to help us finally re-apply and get the CO re-issued.

New construction isn't difficult -- your architect/engineer will handle all the plan review process and get you your permit, and construction costs for multi-family are much less than what you can sell it for (roughly $200-$250/SF to build vs $400/SF to sell for instance).

Can you recommend an engineer or architect?