And when talking to references, I would ask about draws, if contractor asked for any early draws, was able to provide invoices for work complete with each draw, etc.  

what would be the most practical and easier bookkeeping system for a real estate investor when you have to track flips as a project on itself, purchases, invoices, rentals, payroll etc?

Cole, you deposit an invoice for your fee and get paid!

You provide a final monthly financial package, including rent roll, tenant ledgers for any delinquent accounts, final paid invoice copies and any unpaid, copies of active contracts for services, list of accounts (utility, yard service, etc.) that need to be re-established by new PM.

Invoices change behavior, friendly reminders or stern letters rarely do.

The property is .25 acre and was purchased for $1000 at the county auction.The Property Owners Association mailed me an invoice for the balance of the dues forward to me from the previous owner.

it says she pays but does not clarify if they must be in her name then send her a bill as soon as you get an invoice.  

* Are all my invoices uploaded to my owner portal?

Enter a maintenance request, assign a vendor, attach a fake invoice.

However, I would also invoice the owner for supplies (toilet paper, granola bars, etc).