Or are we legally bound to rent her the house if she comes up with the deposit some time between now and her move-in date (Dec. 1). 

You are bound to cause yourself problems.

If you have a problem into one LLC you can loose up to the whole content of the LLC.

In Vegas its very common to charge up to $75 per applicant which is legal but becomes very expensive for the prospective tenant especially if they do not make the credit check or loose out on the dwelling ..

It seems like a great opportunity to invest my money in real estate early, without having to loose precious study time.

cap rate is a loose translation for your yield.

If it isn't specifically spelled out in the contract, you will most likely loose your earnest money if you back out regardless of the reason.

Also, even if you can get coverage, consider that, should the dogs get loose and bite someone, their attorney will try to bring you into the suit along with the owner.If you are willing to let them stay, I would insist on them getting Renters Insurance with the highest Liability limit available in your area (probably $500,000)

"Brokerage laws" are not always bound by statute.

In that book he talks about how he learned the rules of a certain style of martial arts and that by being able to get his opponent to step out of bounds, he would get points and eventually win.