You will want to consult with a lawyer.In regards to your last two questions here's some background on what makes a contract valid and enforceable:Offer: A promise to do or not do something within a certain time period Acceptance: A clear and direct statement that all terms and responsibilities are accepted Consideration: A legal and adequate inducement given in exchange for the promise Capacity: The parties to the contract must have the legal capacity and competency to contract Awareness: A party must be aware of the contract Legality: The contract must be legal in the jurisdiction it will be operating in***Not legal advice*** Steps I would take: -Review contract in detail to understand each counterparties responsibilities (if you are not aware)- Email a copy of the lease to each of the tenants listed on the lease and reiterate lease expectations for termination notice, rent payment etc. - If the lease was signed via Docusign (other esign may have same ability) - you can go to the envelope, go to history and view the IP addresses for each action taken.

Many distributors also offer financing and can give you an idea of what monthly loan payment you’d be looking at.

If anything is obvious like a solid proof of more people living in the house or signs of smoking in the house or if she misses even one rent payment then start the eviction process.

With your Fico and down payment, all you need to do is make sure you pass the debt to income requirements. 

I can make the down payments in the smaller market on cash-flowing deals, but these bigger markets require 40-70k to make a deal the conventional way, and I just don't have that to invest.

Just curious - what sort of down payment do you usually require of US citizens? 

Those willing to go beyond that could be good partners for real estate investors.Traditional banks/Local Banks and non-bank lenders - If they are a portfolio lender, meaning they actually hold on to the loan and don't just collect your payment, then they have the ability to be flexible.

Those typically seeking $30-$50k are for down payments or second position liens. 2.

If you sell a property, and do a 1031 exchange with the proceeds, but don't need all the proceeds for the down payment of the next property, are you taxed on the additional profit that isn't part of the exchange?

I don't like paying interest on my down payment unless I know it's a temporary aid to get a good opportunity.