Budget for all of the direct and indirect expenses.Be comfortable hiring others to supplement what you do.  

Here are the stats:Current payment and rate: $1,807.23 w/4.75% rate 30 years at 4.25%: Savings of $230 monthly with MI 15 years at 3.5%: $1,868.83 (w/MI)15 years at 3.625%: $1,821.84 (w/MI financed)We can comfortably pay our current mortgage amount as well as the 15 year options, though part of our reason for refinancing is to enable us to eventually move and rent out this property (better cash flow), however now I'm considering is there more benefit in doing a 15 year and building more equity that can later be used to do a cash out refi or HELOC?

You could get a Solo 401k plan that enables to invest in both RE and the stock market.

My wife and I are discussing buying our first rental property with the aspirations of having 3 or 4 to supplement our current income and hopefully fund college for our children which are still young.Our plan was to buy a home at 50-75k and rehab it with 20-25k and then rent it for 1-1.2k.

At the moment I'm looking to supplement my income.

Meanwhile the other tenants will be helping pay your loan (ideally partially supplementing the cost on your unit).  

Passive income stream to supplement current retirement income.2.

A webinar would enable showing things that a podcast might not be able to do

I am a teacher and have two fellow educators who plan to working together to flip a house this summer to supplement our income in the short term with long plans of getting out of education sooner than later.

approximately, how much of each down/closing costs(per deal) were you able to recover, percentage-wise, of that money on your cash out refi to enable you to reinvest in another hold?