Definitely vet the team you'll be working with and hopefully have some kind of familiarity with your target market.  

@Judy P.Maybe worth it if you’re a homeowner (primary residence) definitely not worth it if you’re a landlord

It's going to be pretty difficult to create a definitive list of what you're covering and when you're covering it.

If you can get it even Mortgage+HOA/Rent that will be impressive and if your credit checks out you will definitely have solid cash out options.

There's too many buying opportunities I come across daily, definitely not saturated in my opinion. 

The only type of sales job that qualifies for REPS is real estate sales, under the definition of brokerage.Below are the 11 categories that qualify.real property development, redevelopment, construction, reconstruction, acquisition, conversion, rental, operation, management, leasing, or brokerage.If you are full time in sales, then it is unlikely you would qualify.

So sending 100 mailers, lol, is the definition of pointless.

Definitely do your research and make sure to interview your PM.

If the latter, and if I continued to purchase mortgage loans or otherwise lend money, is there a definitive point at which I can no longer reasonably argue that I am not in the business of lending money?

Definitely consult with your accountant before you sell as there are situations where a 1031 isn't worth it.