You should probably start by identifying the target property and have it under contract (or close enough) before you sell the first one.

So....I have this property in Texas that is owned free and clear currently being rented by a contractor who has done some work for us. 

Reimburse my contractors company 150k in costs through escrow, that way I can get more cash out of my exchange?

In the mean time I have to send the same contractor for the heater ugh..This tenant really opened my eyes, as many mistakes we have made, the only thing I was able to really verify was employment, she doesn’t have a “professional” job but she’s making decent $ and drives a 2017 bmw.

You can also obtain electric and gas info easily.

Long-term I am looking for a contractor who I can take care of construction, while I focus on sourcing deals and raising capital.  

I actually only have two contractors that I or clients have used that I recommend.   

My dad is a contractor and he works on properties in Boston and sometimes he shares with me the prices of these homes and condos and it's SO MUCH.

Is a new garage w/ apartment (and running plumbing, sewer, electric, etc) going to cost me a lot more than 100k?

Draws would go directly to contractors once their info is received.