Another thing to add is the regulations, HOAs and Cities are imposing a lot of regulation on short-term rentals or rent by a room, I have seen some HOAs regulate the amount of people authorized to rent the property too.It requires to do a lot of due dilligence to begin with mainly in such big house. 

She is required to disclose it.

If you have a real estate license, are you required to be "registered" or working with a broker or can you be licensed on your own without belonging to a brokerage?

Also, it can avoid filing an amendment.Another great point on eligibility- SEP IRAs require net self-employment income from activities like 1099 contract work, real estate sales, wholesaling, or other self-employment business income.Passive income as you have highlighted, does not qualify. 

Can they bypass this requirement if paying in cash?

@Toby FellowsYou are correct, you need to ‘hang’ your license under a broker in order to practice real estate, and most brokerages require you to become a member of the National Association of Realtors as well.While you are preparing and taking your courses, contact several brokers and interview them to find out who might be a good fit.

The insurance companies might require this. 

In addition to a voucher, we require that the tenant be able to show income at least 1.5 time the monthly rent, as opposed to our regular tenants who must show 3.5 time monthly rent.

Some states make it relatively easy to track down off-market deals, while others require a lot more creativity and persistence. 

Eligibility for the ATI exemption depends on several factors, including:The nature of the transfer: Sales, inheritances, and certain other transfers trigger reassessments that may qualify for the exemption.Timely application: Property owners must apply for the exemption within the required timeframe.