A little more below...Here's What You Can Do:You can ask for doctor's verification of disability as long as the disability isn't obvious to you (this covers emotional support, comfort, and companion animals)You can ask if the animal has any training or certificationYou can issue a 10 Day Comply or Vacate Notice if the service animal is causing damage or other problemsCall RHAWA or an attorney for adviceHere's What You Can't Do:You can't restrict tenancy based on service animalsYou can't deny someone because they have a service animalGood luck!

What training do you provide a new agent to help me get started?

These are professionals with additional training and a stricter code of ethics.

Ask their experience and training, each state has different certifications or licensing.

If the situation is as the OP has posited, it cannot have reasonably escaped these tenants' notice that they've been getting a big break on their rent.They chose to ride the gravy train until the wheels came off.

Underwriters and banks are trained to know what is a primary residence purchase and what is an attempt to buy a rental. 

Think about all the military training you've had.

I'm an investor as well and having your license not only allows you to cherry pick the deals you want to keep but gives you more in depth information on the market along with access to training (depending on your broker).

Would you bet hundreds of thousands on yourself right now, or on a top-rated runner whose been training for decades? 

Do you think their training programs are good enough for someone starting off?