Renting instead of selling my house

[Dan Hobkins]

So I purchased my first home about 5 years ago, and am thinking about upgrading houses in the same area.  The house has appreciated, I have a very low interest rate, and was looking at rental comps for my 3br/1 bath house  which would be about ~100% more than my mortgage.  That's some seriously good cash flow coming in, versus selling.

What are the tax implications of renting out your old house?  Also, when applying for a new mortgage, I would be in my current house (unrented) with no rental history.  Would I be able to apply my forecasted rental income, as part of my earnings? Or is there a way to go about it?