2) If you are a developer or architect, what are the deciding factors when it comes to having a third party review the construction documents?

This includes investors, realtors, our architect, the GC, etc.

You're going to definitely want to start with architect to get a plan set on what you're building for the space and engineering to make sure it's feasible and can be done. 

Hello Amy,I am a licensed Architect here in Chicago and know quite a few people in the industry.

Cash is the ultimate liquid asset.and(things that can be converted to cash--constantly quick)Treasury bills and treasury bonds.Certificates of deposit.Bonds.Stocks.Exchange traded funds (ETFs).Mutual funds.Money market funds.Thinking otherwise could be useful (personally), but "Liquid Asset" is a defined thing.Like a steel I-Beam is a defined thing vs a 2x4 (another defined thing), an I beam could be 2" x 4" but most would spec a Steel I-Beam vs calling it just a 2x4.https://www.wallstreetprep.com/knowledge/cash-equivalents/Is this the Creativity of a top Architect bouncing against the rigidity of Accounting definitions.

Sure, create a budget, scope of work from a GC and architect, set aside 2x your budget and run a new P&L on future rents, that plus the risk and opportunity cost of the investment will tell you whether its 'worth' it or not. 

Hi Steve,I read your post and thought I’d reach out.I'm a 44yo architect working/living in Puerto Rico.I’m interested in getting into RE investing via Flipping and STRs but don't know how to get started, so I am looking to team up with someone from whom I can learn how this whole thing works with minimal risk, while also helping them in any way that I can.What I can bring to the table are my 20 years experience as an architect, the fact that I was born and raised here in the island, and the local resources/contacts with whom I work on a regular basis.The ultimate goal is to start a RE investing business of my own, and although I’ve been reading a lot, I’m hoping to learn by doing.So, feel free to reach out, if you think we can possibly help echo other out.Best of luck!

Because of your unique needs of using materials you already own, you will have to have the plan custom drawn, by a local architect.

I am working with an architect and am almost finished with the plans.I am exploring potentially condo-izing the finished duplex to be able to sell the lower and upper units separately down the road.

Soft costs are going to consist of architect, engineering, permits, and/or anything else that's not involved in the actual vertical GC budget.