For the future, bear in mind that you can't unilaterally change a contract.  

@April Chim, I'm glad you asked this question, as it is a question I also had when getting started (I'm still a rookie, so bear with me lol).There are many possibles ways to approach real estate with little to no money, but be warned, they will most likely require more time, effort, and creativity, than traditional methods.

Please bear with me.

My first question would be are you able to write them a check or do they need a cashiers check when buying these properties?

You should charge as much as your local market will bear.  

Nevertheless lessons are learnt and move forward bearing it in mind.

In contrast, 80 cents on the dollar in a market bearing 80K home prices, most will pass if not all.

It's my job to make sure he doesn't have to pay more than what the market would bear to an arm's length buyer.

Another roofer has suggested using the load bearing portions of the home to build a 2nd roof on top of this one and says it would not cause more stress to the existing roof/rafters and this is a good solution rather than tearing off the old roof.

As an apparent flipper of "budget" houses for first-time homeowners, you need to have a very good FHA lender on your team, that knows how to get deals done, and knows the type of compensating documentation that can be brought to bear to push loans through underwriting.