In the first two, the chain of liability still direct connects to the property owner, which must be a designated person (at some point in the chain of things you will hit that requirement of a designated person). 

He also has a weekly podcast designed for investors, “Refresh Your Wealth”

Creativity, and the understanding of basic math (Algebra and Geometry), allows us as REI's to design these strategies...on the fly.  

I am about to finish building on the lot I sold and have already designed a 3 BDRM/2Bath with detached ADU for myself.

Depending on how Luxury your going you may want to start by talking with some known interior designers in that market segment, they will be able to lend a ton of insight as to trends and who's doing what and whom to stay away from.

I already have a plan/design in mind and would like to have some say in features/finishes.Are contactors willing to have this kind of arrangement? 

They are as follows:• Qualified appraisers• Comparable sales data or “comps”• Gross multiplier approach• Capitalization rate method• Essentials of real estate investment analysis software We prefer using a specially designed computer program in conjunction with input from consultants and comparable sales data.

If so, can the Savings Account for one property designated to hold the Security Deposit accrue interest? 

Purchase price: $85,000 Cash invested: $800 Inside Out Modern - Home Staging & Design

They are designed to protect your interest.