I truly do anything I can to prevent taking money from her in the deal.

Or are there provisions that prevent a buyer from doing so?

You would likely need to talk to an attorney and ask about how that would work since you might be in a bind waiting for the tenants option to expire and be prevented from doing anything until that time. 

That construction agreement may not be valid without a license.Forget any construction financing, you can't give the property as collateral.If suppliers extend credit for materials, they will generally want the address and owner to sign or a licensed contractor with a valid construction agreement allowing liens to be created.You can file your option and cloud title, but that cloud doesn't prevent an owner from selling the property subject to that option, the new owner will be obligated to sell it under the option, but if you fail to exercise it as agreed, they will own the place.

Regardless of the price range you're working in on the retail (agent side of the deal), it doesn't prevent you from investing in homes in any price range.

Here is one that might seem obvious, but can really prevent many headaches later. 

Estoppel is a legal doctrine that prevents a person from asserting rights or facts that are inconsistent with earlier actions or statements.

so how do I prevent from making the mistake of low balling the repairs to much?

Only the owner of a property can obtain a permit - which legally prevents tenants from placing a fire-pit on the property without your consent.  

They do this to try and prevent lender hopping to close on the property.