However, those who can weather the storm stand to benefit from potentially lower interest rates and growing demand for rental units.Despite the challenges, there are opportunities for buyers with sufficient resources to capitalize on the market's current conditions.

My brother-in-law has been financially successful in real estate, but to avoid family issues, my wife and I have resolved to be self-sufficient.

It is very hard to do an FHA 3 & 4 unit currently because it has to pass the self sufficiency test and with where rates are at it is unlikely to pass.

I’d think 4-5% would be sufficient for vacancy.

Also, with a Traditional IRA you have to make dang sure you have sufficient liquidity to take your RMDs!

Are the rents in the area where you want to buy sufficient enough to offset your costs of living on one side? 

@Erin Spradlin - I agree, landlord insurance isn't sufficient, a security deposit and umbrella insurance is needed too.

The plumber says the pump he recommends is 1/2 hp should be enough as it pumps 21 gallon per min and should sufficient for the 4plex.

My D2I will be sufficient based on the book.

You can find other more sophisticated calculators but the biggerpockets one has been more than sufficient for me.