Until recently, they were collecting rents in person, but they are no longer able to, due to advancing age and disability.Does anyone out there please have some candidate property management companies, that are reputable and honest, and would be willing to service this level/number of apartments?

First, if the closing drags on because of bank paperwork, you don't care because you are collecting rent. 

What is the best method of collecting HOA dues?

I have a collection of 4 buildings (still negotiating 3) on a D+ street that I believe some reasonable aesthetic improvement could attract a C- crowd.

I started this project hoping i could efficiently review the most amount of properties in order to maximize the potential investment options to bid at auction....this is what I have so far.First thing i did was to create the listings, I matched the properties been auctioned with their corresponding pics and the property specs (rooms, size, floors etc.).Second, for each property I automated the data collection process from public records and created a report with: Foreclosure info, owner info, taxes data, liens including mortgages , satisfaction of mortgages,  assigments, violations and permits and court dockets.This data is updated daily to capture new filings (specially the dockets to capture bk and motions to cancel sales)Now that i have the data i can apply my personal "preferences" to go through the report and in a few minutes discard  properties that have certain attributes I "dislike". 

If you're willing to wait and don't need the cash, you can go the payment route and collect monthly payments.

You can obtain pricing now, or wait until you have a few more months seasoning – as only two payments have been made so far and that will come up in the evaluation.To receive a quote, a buyer will ask:Property addressProperty type Owner or Tenant occupiedProperty selling price and down paymentBorrower name(s)Copy of the note and mortgage/deed of trust (or contract if a CFD, land contract, etc)Closing statementWho's collecting payments (you or a licensed servicer, title company, etc)?

Scam artists that collect up-front fees may not actually provide any of the services promised, or may even disappear overnight.

Vacant is provided by the us mail service and is defined as not collecting mail for 90 days.

I collected some contacts, asked a lot of questions, watched a lot of youtube.