Real estate sales is like any sales: your reputation will play a huge factor, which in turn becomes a word of mouth situation.

Enviorment has a huge factor on that.

That could change depending on where you buy, what you buy, and some other factors...but that is probably a good ballpark. 

I am currently living and working in the Denver area as a designer and am working towards architectural licensure.

I've seen designs for a soundproof wall where top and bottom plates are 2x6 and you put 2x4s on alternating edges every 8 inches (16" on center for each side).

Yes this is the cost of doing business, and you should factor your business such that your taking these additional costs into account.

What other factors should I consider?  

Which we are not going to put in a new furnace if the one that is currently there still functions.2) My design work of what the latest trends are is what really gets people excited and thru the door.

I know there are many factors that come into play. 

I love technology and design, so I figured I would get my Masters in Architecture, and eventually be an architect-developer.