Commerical Development - First Project

[Nate O.]

So I'm about to venture into uncharted territory for myself in the commercial development arena and I'm looking for a crash course on the development side of the project. I have extensive experience in creating buildings (registered architect) but have never really dealt with the financial/investor piece of the puzzle. 

-What I'm looking at project wise:

-$12 mil dollar new commercial office structure (includes cost of property, demo of existing structure, -new construction, build out, holding costs) - higher density urban location

-40k sq. ft. to be rented out at $14-20 sq ft.  per month

-major tenant is on board for 35k of the space at said rates assuming the project falls into place

-2 year construction project

My questions mainly revolve around the financial aspects.
What are main numbers that stand out to an investor in a pro forma?
Does it typically make more sense to look at private investors rather then bank financing?
What types of rates would an investor be looking for a ROI on a project like this? 10% 12%?
What amount of money down (skin in the game) would investors be looking for from the developers?

I'm sure I am missing a ton of relevant information. I'm in the process of putting together all of the numbers for the pro forma so I can get this in front of the right investors. Thanks in advance.