Talk to multiple lenders. If you live in one of the units and if there are 4 units or less in the property then the downpayment may be very small or included in the mortgage.
Nope, down payment can't be borrowed from some other source.
First of all, for FHA you have to live in the property to get financing on it. Second, the down payment can't be borrowed, but it can be gifted. The key is to document the gift properly so you don't run into any issues with the underwriter.
For one of the best explanations of how to properly document a gift, check out the following link (not my site):
@Mark F. is right. You need to be "gifted" the money. They will scrutinize it to make sure it's a legit gift.