How will lenders view the mortgage on my 1st house when trying to by my 2nd house?

[Easton Hill]

Hi Folks, 

I am looking to move out of my first house and convert it into a rental and purchase a new home in a new city were I will be moving for a new project. 

House#1(Current residence): Value - $350-380 w/ 230k in a FHA loan at 3.5% = ~$1350 PITI + HOA with water,sewer,trash being $200 or less. Rents in the area are $2000-$2200

Additionally we have saved up 6 months of monthly rental expenses in a "rental fund" to get us over any vacancies and unexpected issues (~ $9300) and plan on adding a $300 monthly maintenance reserve from the rental income to the fund on an indefinite basis. 

I feel comfortable saying that it will cash flow between $200-400 a month. 

Now this is all hypothetical as I don't have a renter in place yet and still live in the home. 

The plan is to move to the new city, rent a temporary place, start the job, rent the old house and begin looking for a house to either build or buy. 

So my question is how will a lender look at my first house assuming that we have it rented? Will they include my first mortgage in my Debt-to-income ratio? Will they count the $200-400 a month as personal income?