The person that normally contacts me is the executor/administrator and this is usually a family member.

Of course, the current administration would rather be responsible for you, since they know best.

Inflation, deflation, I still have a house and that house is something useful.Stocks, and even money, can turn into toilet paper under adverse conditions.Of course, the way the current administration so going, they might decide that I can't get tenants out, no matter what, or even decide to give my house to my tenants.

I see no problem with allocating the expenses for your general administrative costs among your various properties if those costs don't directly relate to any specific property.

Great tax advantage to loan on 401k verses owing income tax (I am not a CPA or tax advisor but call your 401k administrator they have tools online to show you the math).

And so long as you have an administrative account you can create guest accounts for the tenants and assign them their own security code without having to risk them being able to change any settings or add accounts that you don't want changed

The next few questions you placed, will somply be more complex to solve, most important is not only the money being collected, but also making sure you stay in compliance with the municipality, this could mean many or very few administrative items.

So, if you have to fire or substitute a trade, you can do that an administrative fee (less than pulling the permit).  

If you are getting paid a % of rent you need to include some administrative functions with rent collection. 

It might be one the way, but it ain't here yet.Everything else will simply be files, storage, manipulations and formulas which aren't really rocket science.So, as to your question, what aspect of administration of real estate which is similar to other businesses are you interested in?