My question pertains to your third post.

AirBNB specifically recommends language pertaining to allergies and service animals - you can state in your listing that you don't accept any animals (don't say "pets") due to allergies and it being a health risk to you or a family member.Again, definitely look into the laws yourself, but between this being your primary residence, your only STR, and you having allergies, I don't believe you could be required to accommodate service animals.

If you have investors, the Operating Agreement should spell out many issues pertaining to the ownership and operation of the LLC.I do NOT recommend trying to cut corners on your LLC. 

A lot of the time, factors pertaining to a property willdetermine what carrier an agent can get you covered under or not.

I believe it's a contract pertaining to the lease of real estate for more than 1 year has to be in writing.See:https://statutes.capitol.texas.gov/Docs/BC/htm/BC.26.htm

However as your questions pertains to ethics being a realtor/investor, I would say no you should be fine.

You shouldn't be having DTI issues provided you are buying good cashflowing properties, overlays pertaining to the "counting" of rental income is likely what is at play.

However, the part of rent control that pertains to asking them to move out when the lease is over still applies.

I highly recommend you consult with a knowledgeable CPA in the area of international/cross-border taxation especially as it pertains to estate taxes.You are correct - a nonresident alien is generally subject to an estate tax on their U.S. situs assets of 40% on the excess of $60,000.

@Michael Noto"From experience, even if the tenant is in the wrong do you think they have $10k or even $5k laying around to pay"That statement, pertaining to whether you charge the tenant, is irrelevant.