When loans were called, was it due to specific triggers like delinquencies, insurance lapses, or low-interest rate portfolio loans held by smaller banks?

As I see it, the only ways that real estate pays you well in the first 3-5 years is low to no leverage or a strategy that requires more work (short term rental, mid term rental, rent by the room, etc.).  

@Sakib KhanRecommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

Is there a way to have No money Down or Low money down? 

say you find a solid property in a low cost market for $200K and you buy it.between down payment, closing costs, rent ready / spruce up costs, and lease-up costs, you're probably going to need at least 50-65K in cash. 

We have one or two quality wholesalers that we are open to working with.

The type of the neighborhoods where his properties were located didn't fit in with my plan but he did well and the purchase costs were low.

With HML at least you in theory can vet the property and keep a low LTV to ensure you can be made whole.

Rates are high, usually in the high 8s or low 9s, and you may pay 2-4 points on the loan. 

An eviction will make it challenging for her ever to find a quality rental in low vacancy areas.