My father still lives in the Poconos half the year and it's still the same way 40+ years later. 

The seller, who had inherited the home, wanted to sell and move in with her elderly father.

My husband took on the father role to my 5 year old daughter.

Assessment has nothing to do with what you paid anyway.You father can sell the house for a dollar in that sense does not mean they will look at that number to decide the value of it.

My father is pretty close to retiring and has had a very successful last couple of years of his career.

We purchased the complex from my father who had many section 8 tenants during the 20 years that he owned it.

My father in-law has not been living in his house (primary residence) for nearly a year.

If there is an estate or something else that lays claim to it and you gave it to the father, it might cause some issues. 

I think you should work in the franchise like your father wants.Learn the business, what if you worked as many hours as you can, work 80 hours a week or even work 100 hours a week (child labor laws might limit this ????)

I would check with your lender to confirm if 0% can be used for 3 and 4 units...they might require 5% down.SFR investment with rehab can also be a great way to invest in real estate. it just depends what are your strengths and goals and which strategy will best serve you.buying a home a year is normal for some. depends on what your goals are.Id think of it like planting a tree: being 25, time is on your side. if you have a solid income with healthy DTI, I would suggest taking advantage of it by house hacking small multi in A/B market and let father time be your friend.