Some might do more of one type of home than another, or specialize in a certain price point or age group, but they generally will have similar quality materials and designs. 

I will be able to build this house for about 45 k (My family doing all the labor and using our connections and getting materials at cost) then with the money that we would have paid a contractor build a second home to rent.....2) Build said home^ and pay off my existing mortgage on my house.

Even if you don't have tools you're still looking at less than $200 in materials. 

With a contractor husband, you should have your work cut out for you, whether your focus is fix and flips or rentals.Podcast 48 with Darren Sager offers some great advice for taking rental property and 'hardening' it, specifically what types of materials last a long time. 

I buy all the materials and do time and materials whenever possible so they don't have to build in "what if" hedge. 

There are a lot of learning material on the site. 

Here are the names of those you should NOT use as contractors as all of them are crooks - they take your deposit money (materials, 1st phase labor) and simply disappear

The differences with what we are doing and fixing and flipping retail is just a matter of material upgrades and finishes.

I trained her and showed her how to find great deals, and we provide all of the necessary material for her to do a proper job.

Seller further certifies and represents that Seller knows of no latent defects to the property and knows of no facts materially affecting the value of the property except the following: (Description of problems)______________________________________________________________________________________________________________________Buyer has inspected the property and HAS NOT RELIED UPON ANY REPRESENTATIONS MADE BY ANY REAL ESTATE AGENT in describing the property, and Buyer accepts the property in its PRESENT AS IS CONDITION, except as otherwise specified herein.13.Occupancy:[] Seller represents that there are no parties in occupancy other than Seller.