You can find some useful calculators here: http://mortgage-x.com/calculators/default.htm
All of the online calculators are just generic. the best way to get the best rate is to find a great loan officer and ask your questions. The problem with online lending is that they often change the terms right before closing, if they even show up at all. Imagine that you are ready to close on your dream house and your e-lender sends you a little note that says, "We were unable to get you that low rate, but we can get you this rate..." Now, you are committed to buy the house, and they figure that you'll go ahead and swallow the bitter pill.
Real Estate is still a personal business. All the fancy web sites in the world can't substitute for a great Buyer's Agent and a strong Local Lender. You need someone who is accountable to you for getting you the best possible result, and available to you to discuss the process. We just don't see that happening with the online bait and switch crowd.
You can also get helpful information on VA site:
Just put in all your information and it will price it.
If not, I can do it manually.
Email me your details to email@example.com