Tax Question - Another house

[Edward Jones]

I have 2 houses, the mortgage on them is $5k , the first one is a rental and the second is owner occupied but i also rent out the rooms. 

I want to know about income / debt ratios and tax. I want to buy a 3rd house to live in and make the first 2 investment. The bank will let me borrow but my debt income ratio should be less than 45% so is this math right..

1) The mortgages on both house is $5 PITI and the rental income covers that.. so on this $5 does that mean i dont have to pay any taxes since it is mortgage?

2) and than on top of that $5 , i want to buy a $430k house so does that mean i have to make $10k per month on top of the $5k? so $15k per month to qualify? and I only ahve to pay tax on the $10k right because the $5k is for the mortgage? 

how does it work?