Had to shut off my rental phone after that and had over 20 messages in voice mail. 

Just make sure to get an invoice to justify the payment for tax purposes.

If you did anything like that after you bought the house, or the seller had work like that done to the house shortly before it was sold (and you have the invoices to prove it),  it might help to make sure your insurance company knows about it.

For example, if I hire an electrician (separate from my general contractor) to upgrade the electrical panel, do I need to have him sign an independent contractor agreement or do I just fill out a W-9 and sign an estimate/invoice for the services? 

My research has led me to believe that QuickBooks online is the best method, however, it seems as though QuickBooks deals a lot with sending out invoices.

TenantCloud does this great with invoicing, late fees and accounting all built-in and included.

Here are the few benefits of having a virtual assistant Screen your e-mail and respond on your behalfSchedule and confirm your appointmentsBook your travel arrangementsMake calls on your behalfPerform miscellaneous researchFill out expense reports and track reimbursementsCreate invoices and post paymentsManage any projects you don’t want to handleThe best part of it is that you have the option of hiring a part time or full time VA depending on your load work.

I've heard that invoicing and late fees can be applied automatically.

Do you send an invoice?

The first property just got rented out and the first invoice from the PM was a def surprise.