Most of these program qualifies borrowers with income and very few DSCR.

THEN, I plan to purchase the second home using a FHA or conventional loan (3%-5% down), for which I will likely pay the monthly cost out-of-pocket, maybe with some rental income support if it is a duplex.My concern is, I do not want to spend my savings or weigh down my debt-to-income ratio so much so that I cannot qualify for and pay the down payment and closing for the lending on the second home.Questions: - With the first home being multi-family, 75% of the rental income (or potential rental income initially) will relatively either maintain or boost my debt-to-income ratio from lenders' perspectives, right? 

I would speak with a loan officer to get an idea of what I would qualify for with that level of student debt. 

This will help you understand the qualifying requirements, key factors to consider when purchasing, and how to assess whether a property might be a good investment at first glance.

At least 2 US credit scores required to qualify.

(Could be more than just two) So just be aware, you can use the sec 8 income to help with qualifying for a DSCR loan but you could very well end up with a higher rate.  

Your ability to qualify depends on income, credit, and lender requirements, but leveraging your equity makes your request more feasible.

I would be very careful in working with a 1031 Exchange Qualified Intermediary that provides ("sells"0 replacement property solutions as part of their services. 

Even so, we might not qualify for a house/cottage in the 200k-300k range. 

A lot of qualifying questions for any potential tenant.Having said the above, I ask for some "standard" things, such as the names of everyone who'll be living at the unit.