The HOA is an American thing, if you are thinking about management fee's well they vary a lot, ours are about 3500 baht per month which I don't think is bad considering what we get and it is a high end project, as somebody has mentioned go and stay there for a couple of months, a lot will depend on the size of the unit you decide to buy, ours are 60sqm but I'm not sure I could live there full time although lots of people do,
As for running a Airbnb remotely you wont make enough money to cover the cost of hiring a co-host/cleaner we are fortunate we only live 5 minutes away, let me tell you need a full team and electrician/plumber/A/C guy and Airbnb guest will expect it to be fixed now!
In the past we have had other host ask to take care of their property, they have read our Airbnb profile and seen all the excellent reviews I have declined them all.
Some projects do have a management team they will rent it out for you obviously at a cost, I know they have were we are, they are not shy 500 baht to change a light bulb,