Is there a diffence between a loan for an investment property and that for a home that the purchaser planned to live in?
Yes investment property require more money down. We also have financing for 2nd homes. Those loans are for people that aren't going to live in it more then 6 months out of the year but aren't planning on renting it either. Those require less money down then investment property and...

Can I get a streamline FHA refinance if underwater?
yes we do have some lenders that will do more then the house is valued.

could i go zero down for VA with a 620 credit score?>
Yes you can qualify for a VA loan with a 620.

can multifamily housing qualify for VA?
Yes VA allows 2-4 unit properties as long as 1 of the units will be the Verterans primary residence. Hope this helps.