How to your analyze the deal and add some margin so you secure profit?

My question is; Are our text messages considered a contract even though it never outlined when rents were due or any other variables, other than when she could potentially move in and what the security deposits would be?

All of the above, for present autonomy and future security.

Each tenant could have their own somewhat secure area.

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

There are always sellers who need the benefits that seller financing can provide them (income, capital gains tax deferral, a reasonable return secured by a tangible asset, etc.). 

This way you will have security that once you do find that good deal, you can have funding ready very quickly. 

@Clayton BrayIt appears that your wife has her own business -The difference between having your own business and being an employee is as an employee, the employer is taking out federal taxes, state taxes, social security taxes, medicare taxes as they are earned.There was many tax law changes recently that made those having their own business have friendlier tax laws.

I pitch myself as having a much better value than anybody else (lighting, security fence, 24/7 access, flexible office hours, free lock/keys, etc...)

For example, the tenant could claim the Seller allowed them to paint the walls black or that their security deposit was twice what the Seller claimed or that the refrigerator belongs to them.