HUD also requires a good loan prequalification letter from a lender that includes the property address in the letter. There is an assumption that this lender has given you a list of your closing costs and that number is one that works for you.
There are limits on the $100 down payment program ... it may not apply to the property you are trying to buy. You should be clear about this with your real estate agent BEFORE you submit an offer.
I suggest that you sit down with your real estate agent and lender ASAP and be clear about all of the monies that are involved in this transaction, and be clear about inspections and all of the steps necessary to get you to the settlement table.
I wrote a consumer book, "HUD Homes for Sale - A Complete Buyer's Guide." (All proceeds from the sale of this book are donated to CARE for humanitarian relief.