I do that personally...and my employer does it as well. 

HiCan I as the administrator of the deceased estate use a PO Box for the administrator address and not my personal address?

I also own a personal vacation home in the Poconos.

You need to look at your personal risk/reward factor. 

For ex, of more than one person is in need of service how would that be prioritized?

So I bought this house for me as personal residence & did live there the 1st year.

In person, phone, email.

And we've done it with the stock market almost fully recovered back near ATH's, the housing market staying strong despite huge changes to interest rates, etc.Maybe it's all a mirage and one last hurrah to hold on before the big crash everyone has been anticipating finally does come, and I've been a bit of a doom and gloomer myself, but I think if you'd asked a year ago if it were possible to get back to 3% inflation in a year with the stock market within 5% of all-time highs and housing prices still within 5% of the peak every single person would have said it was impossible. 

From a tax perspective, an LLC is a disregarded entity (meaning it is reported on your personal tax return) until you elect for the LLC to be treated otherwise.

I personally know 6 people who have quit the W2 jobs around the age of 40 (picked the right properties and benefitted from appreciation)  and age 30 (high income earners who leveraged and scaled quickly) from real estate.