You might pay $100,000 less for a resale vs new with the same rent.Most new home communities do not allow investors.Many if not most of the HOAs for the new home communities are not friendly to investors. 

Buy Box:- Creative deals only subject to deal - < $600,000- >2000 sqft living space- No HOA- As many bedrooms as we can get - At least 2 bathrooms- ADUs are a huge plus- Cosmetic rehab is preferred but will entertain light rehabs under $10k.- Close to transit preferred- Close to jobs/shopping

I moved into a condo with an HOA and they have a property manager.

In any event some lenders will count up to 75% of gross rents as income while recording mortgage, taxes, insurance, HOA fees as "front-end" debt payments.

For example, he said his brother has looked at homes in the Dallas area that have depreciated in the past 12 months.I will likely have some vacancies, and maybe evictions.I will need to spend money on repairs and maintenance.Other expenses: property tax, HOA (hopefully not), insurance, legal costs, and closing/selling.

Something without a HOA is best.4) find a local group and go to some of their meetings (if you are buying locally)5) contact a realtor who works with investors and look at a few places after you've run the numbers and be prepared to put in offers and follow through

If you're applying for a Conventional/FHA/VA/ or USDA loan, then they will do a "global cash flow" where they take into account your PITI (Principal + Interest + Taxes + Insurance (hazard and flood) on all properties (second mortgages included), HOA payments, car payments, student loan payments, credit card payments, and installment loan payments in the numerator and your gross income in the denominator.

My HOA has said they're not responsible, but I have been told that the issue won't be solved unless all the units (less than 10 total), are sealed. 

While going through the HOA document I saw that the HOA secretary and president are from the company that purchased the complex from the original developer.

If the HOA required you to obtain their approval, did you hire an attorney?