Several options exist, including tearing down the primary residential home and building two duplexes.

It also makes certain capital expenditures, such as roof repairs, can be "lumpy" in that they can be large in one year and non-existent in the next (although they're guaranteed to occur if you own property long enough).  

Absolutely get a title search/commitment.

But you must have a pre existing relationship with them. 506b also has onerous reporting requirements like a yearly financial audit that will run you $10-$20k, so if it’s less than $1M a 506b may not be way to goAnother is a reg a+ offering but that costs $100k+ to setup and requires registering and review by sec.If you want passive investors who are not accredited there are not many options.

I just did 2 multifamily deals with existing tenants, both with estoppels. 

Once enough equity exists in a property, maybe every 5 years, either do a 1031 exchange or a cash-out refinance.My finances:Gross monthly income: approx. $12k, plus an annual bonus that averages to roughly $1k/month (if that can be factored in)Current monthly debts (including mortgage, property tax, insurance, car, child support): approx. $3.5kDebt-to-income concerns:Time for some napkin math for a concern that makes me worry whether this goal is actually possible...Assuming all goes as planned, I worry about eventually hitting a wall where I'm unable to qualify for new mortgages at a certain point due to how the investment properties' mortgages will affect my debt-to-income ratio. 

I am resident of New Jersey and bought my first 4-family (in Somerset) last year at 22 and was initially excited to get the ball rolling, but good deals have seemed to be non-existent since.  

Wrap the existing loan in a new loan to your buyer.

You also have have to be careful of title junk fee's they exist and it may make some title companies angry but they charge for some unfavorable line item fee's. 

Laws can change though If you have an existing permit prior you are often grandfathered in- so it makes sense to get the permit even if you are on the fence.