some brokers offering intrest only options for the costumers, simply because you are the first time buyer and propably your mortgage payment with taxes and insurance is much more, then you paying rent right now(big payment shock). you can add any ammount to your regular monthly payment and pay down your principal down if you wish. this way he offer you the option to lover you payment (just in case you short on cash), but if you want you can send more money every month, once a year or whenever you want. if we talking about second mortgage even now you thing ,that you going to stay in your new house forever- statistics say that people move to the new houses every 5-7 years. and believe me your life situation can be diffrent in a year or so , and it's not much likely for you to not refinance your house (you will need cash to pay some bills, sickness, unemployment e.t.c) or simply the mortgage rate will go down. i will be not worry about ballon payment on your second mortgage.you have 15 years to go.
in a year you will have some equity in your home and if you will apply for new mortgage your situation will be better , than today and you will qualify for more programs, than today. think about that, the lender wanted give you money to buy the house and you don't have to put any of your money. by the rate they offer you i assume , that you will go with the program no income verification, so the rate is not that bad- if i i am mistake- check other places. remember also,that with regular 30 year fixed mortgages for the first 3 years you pay down principal of your loan 1% per year. you can see principal go down in about 7 years.you have to ask yourself the questions how long we going to stay in this house? can we easy pay our mortgage payments? are we thinking about childrens and we will have only one income to live from? go back to your broker and ask more questions about mortgages so you will undrestand what will be beneficial for you what not. i hope this will help you to make right decision and 30 yrs fixed mortgages are not always right for diffrent people.