Additionally, I’ve been wondering if it might be possible to create an LLC, rent my house to the LLC through a formal contract, and then have the LLC operate the Airbnb.

When an IRA borrows money, it needs to use a Non-Recourse loan.

Additionally, you may be asked to show some availability of liquid cash/assets to weather a storm in case something unplanned happens. 

I'm concerned that the combined load of heat pumps and ancillary heat strips, along with other appliances, might exceed the 100-amp capacity during winter.As part of our future plans to add a third unit and separate the utilities, we intend to install two additional meters: one for common areas and one for the new unit.

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

Any additional permits?

They probably got the Golden Visa where you only have to spend 500k on real estate to qualify and you get citizenship in addition you only have to spend 2 weeks a year in country. 

IRA funds can be used to make investments only; they can't be used to buy a residence.

However, if one property is overseas, there might be additional considerations to factor in.

Watch out for fine print that requires an additional fee at closing - this is a huge red flag and how most flat fee companies make money.