I have to agree with the other person who recommended waiting until you pay off debt and get your credit score higher. At 630, your score isn't bad, but it could be improved. And the fact she doesn't have credit at all will hurt your chances for the best rates.
And if you could save some down payment, the more the better. You still may qualify for a 100% financed loan, but regulations have tightened on those lately and your options are fewer than they were just a few months ago.
If you really want to go forward now, I have one big piece of advice for you. Don't worry so much about going with a bank, a broker, or a mortgage company. Worry about finding someone you trust that you are confident will get you the best deal possible.
Ask for referrals from your friends, your family, your coworkers, etc. Referrals are a huge part of the mortgage business and you really need to trust the person you are working with. Do some research and you won't go wrong.
Good luck with this. I recommend waiting and taking care of your finances, but if you decide to buy now, work with someone you trust. I've included a link to our first-time home buyer's guide. Many of the points you touched on in your question are explained in detail here.