Once you start supplementing income with rental income your tax returns get messy for some lenders and they dont want to spend the time needed to make a deal work. 

There are some great replies in here already but I would also want to suggest the use of virtual management software as a supplement to traditional management as well.There are some powerful software tools out there that essential manage all of those units from your computer screen (collect rent, process maintenance tickets).

Can I do an umbrella policy without doing a traditional policy or are they supplemental policies?

Here you're hoping for appreciation and the fact that you've put such a large down payment on the property the majority of the rent is actually going towards the principal versus interest.IMO there's pros and cons to both strategies... one is very effective if you wish to build wealth and a passive income, the other is a good strategy to have if you already HAVE wealth and want to supplement it with a passive income.

We're interested in hearing investors' opinions and experiences, as far as using pay-per-lead as a way to supplement their deal pipeline (including success stories, negative experiences, recommended companies, pros, cons, etc.).

Not to mention the supplement in income.

My goal is to create supplemental income through REI. 

If they're able to walk upstairs, they're able to handle your house.I ask this partly because I'm 64 years old, facing 65 real soon (and if I get one more advertisement for Medicare supplementation in the mail I'll throw up) and I'm managing my own two story 3/2.5 house just fine (along with 16 rental properties, including doing the yard work in empty rentals).

Supplementing the mortgage that way. 

Having a good income to supplement your investing can give you a huge advantage.