Pre-qualification means nothing at all, it's always been a worthless piece of paper. You should have been pre-approved (also free from reputable lenders) before you ever made an offer, and both your agent (assuming you had one and the listing agent apparently don't really know what they should be doing.
If you've made an offer then you should be applying for a mortgage as you have a defined period of time (the due diligence period) listed in your Offer to Purchase and Contract in which to secure your loan. It sounds to me as if you're applying for a mortgage and this is why the lender is rightfully requesting money.
In North Carolina buyers use attorneys to close transactions, you don't have a choice and you should have had the entire home buying procedure explained to you before you ever made an offer.
I read your email and shudder, as it's apparent you don't really know what the process is, what your legal obligations are, and what the financial risks to you are. You don't seem to be working with anyone here in North Carolina who seems to know what you should be doing and I can easily see your transaction ending in disaster for you and everyone involved.
You need either an experienced buyer broker (Which it doesn't sound like you have) or at this point an experienced real estate attorney to represent you and to answer your questions and help keep you out of financial trouble. Stop wasting time on the Internet, and find yourself an experienced attorney today. Your lender might be able to help you with some names and numbers.