At the start of 2019 we started the process of designing the house with our architect. 

Once you've run a series of design solutions, pick the one that feels the best for you to serve as the Highest and Best Use of the Property.Once you've done that, you need to confirm the Cost (On-Site, Off-Site, Hard Cost (slab up), Soft Cost and Financing Cost (Bank Interest, points and fees), Income and Operating Expenses.The next stop should be a Land Planner that can give you a few design concepts.

It has a number of designated freehold areas where foreigners can buy freely.

@Danielle Polen I do a lot of design and permitting work for Blue Star as I'm their Architect of record. 

Style of a structure is in the eye of the beholder to an untrained eye, including mine at times as there are technical aspects of design that can overlap, the 50s and 60s styles being mixed.

Add to that the hassle of design, planning, permitting, etc.

Is there a specific type of designer that you use, or is an "interior designer" who I would be looking for?

The simplicity of complexity of design will drive the hard costs.

I loved the Idea of Design+Build but I didn't mesh well with the owner and parted ways pretty quickly.

My wife and I are starting the process of designing an ADU as we figured it was a no brainer for added rent and the potential property increase.