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.

Before graduating from College, I was in no way ready to take on projects and be liable for what I design/draw.

This is by design: a contractor that doesn't have established business lines of credit and/or employees to get started on a job without payment is highly likely to be paying for the last job with my down payment.

I am no pro at interior or exterior design.