Is there any benefit to establishing a “parent” LLC that would own the separate property LLCs?

No matter how good your systems are you will likely end up in that city a few times per year at least, especially in the early years.With that being said, once you have your core team established in long-distance investing, it becomes much easier and problems equal google searches for vendors, phone calls and book keeping in your life (project management) vs. swinging the hammer or fixing a toilet yourself because you're forced to put those systems in place.I live in a similarly expensive city and would honestly be stoked to find a duplex in Denver for $600K!

For extra insurance, you may want to start giving 10% of your bookings to another cleaner to establish a relationship in case anything happens with the 1st cleaner. 

If you're established enough as an investor that you're already doing projects and own assets, it's highly likely that taking the time to save 10 cents per letter by doing it yourself is not worth your time.

Some parts of the country it makes sense and some investors will have different uses or ways they are willing to pursue.An Investor has a lot to consider upfront and during their due diligence period buying real estate.

Your input would mean a lot to me.

Depending on location they can cost a lot to replace but when you factor in what you save from paying sewer bills it’s cheaper in long run.It would not stop me from buying a house

Although, I think it would drive up the cleaning fees and, in turn, the airbnb rates to have cleaning/PM companies that establish and maintain a higher standard of work.

Along with the other ways to acquire properties you mentioned such as Sub To or assumptions.It's tricky because there is a lot to flipping and acquiring real estate and financing that I'm (unintentionally) ignorant about.Lots to learn.

Does anyone have any recommendations for how to collect monthly rent payments digitally into an established account?