A) This is what Realtors are for! I wish you had gone into this with a Realtor to help you and guide you from the beginning. They could have also hooked you up with a good lender who would explain all this stuff to you before you put a penny down.
B) NOw, generally, money has to be in your bank account for 2 months for it to be seasoned. When you signed the contract, I am praying that it had a contingency in it that if you can't get the mortgage for whatever reason, you would get your deposit back. Since the builder really doesn't want you to walk away they hopefully will not mind a short delay.
Here's a hint, ask the lender if you can use a GIFT from a family member. Some loans will allow that.