Seeking to purchase a mixed-use building in NYC w/ Seller Finance

[Andrew Gordon]

Seeking advice. I am hoping to purchase a mixed-use property in NYC that has two rental apartments and one store front all occupied.   We have a close relationship with the owners of the building who just inherited the property from their late mother.

1. If they offer seller financing to us, what are their tax implications on being paid out over time? I.e. Is there any negatives for them financially speaking? Any advantages? 

2. What are other options to finance a mixed-use building? The rent roll is below market, and the building itself needs a good amount of work (Estimate roughly $500,000+ worth of work)

3. Are there any Fannie or Freddie programs?  I saw there is a "SAL" program but there are not enough residential units in our buliding to qualify.

Any advice is appreciated to try and finance the purchase.