Cashflow is what's left over after you factor in repairs, capital expenditures, vacancy, property management, principal, interest, taxes, insurance.So it sounds like your not running numbers correctly - underestimating CAPEX which leads to over estimating cash flow. 

This money can used by the Landlord to pay their mortgage, set away reserves for structural and roof capital expenditures and most importantly, put money into their pocket.

Mortgage, Taxes, Insurance, HOA: $3040.37Estimated rent: $2475Total Expenses: $3660.12Vacancy (5%): $123.75Repairs (5%): $123.75Capital Expenditures: $100Property Management (11%): $272.25Information when I bought the house in 2022, new constructions Purchase Price: $373000Purchase Closing costs: $4662Current home value: 400k-420kCash Flow: $2475-$3660.12= -$1185.12; -$71107.2 at 5 yearsCash on Cash Return on Investment (CoCROI): 0%Appretiation per year (6%); $535,290.23 at 5 yearsEquity: Loan value $345,089.53 at 5 years; $190,200.47 in equity at 5 yearsLoan Value today 6/2024: $368,201.59Total ROI in 5 years= (Total profit/Total Invested capital)/ Time (in years); Total profit: $190,200.47Total Invested: $71107.2 (neg cash flow) + $42757 (closing sale costs)= $113,864.20Total ROI (5 years)= ROI 67%, annualized ROI 10.8%My biggest concern is that I am relying solely on appreciation and assuming will appreciate at 6% per year. 

.- the current rent will be around: $3700So we will have a difference of $2300 + additional fees like garbage, cap expenditure, rehab loan for the 4 units ( around $350 per month ) and others.

And while that depreciation may be disguised by inflation, or area price increases, money does need to be spend as systems such as HVAC need replacement, roofs need to be replaced, and capital expenditures such as kitchen remodeling are needed for the asset to be rented at a profitable rental rate.

Those numbers would be ok, but do you have money for the downpayment, closing costs, capital expenditures, 15k for reserves?

You may drastically lower your living expenditures and increase your capacity to save for future investments by renting out some of your units while you live in others.Starting with a duplex or triplex is a sensible choice, given your aims and money.

Your capital expenditures should be low, especially if there is a warranty on the work.3.

For emergencies, I could move money from my 401k to an IRA to cover vacancies and capital expenditures.

With $60-70,000 worth of upgrades including capital expenditures value will stand at $800,000.