I have found that even many high-end homes have ADUs or au pair suites that people like to rent to traveling nurses, professors on sabbatical, grad students, their kids who come back from college or aging parents (likely no rent in that scenario).

The $100K would be added to your taxable income for the year and there would be an additional 10% penalty for early distribution if you are under age 59 1/2. 

Figured with the improvements, age of the unit (2005) and the fact it’s a condo with all exterior maintenance on the HOA that there wouldn’t be much out of pocket factored into maintenance costs.

My goal is to be able to rely on income a from real estate and other investments to cover my monthly cost of living by age 30.

It is challenging as kids have a finite window at such a young age to determine what they want to prepare to do for the rest of their lives.

The earlier this year, I had to replace a water heater due to age, so asked for a quote. 

Depending on age, it could be clay, which is particularly susceptible to breaking / blockage.

As for insurance - that’s highly dependent on the building age, construction, and location - an agent can give you a quote in a day.

@James BoprieI like the idea of giving the waitress your card before you sit down.1 Listen more than you talk.2 ask if he could go back to xx (fill in your age) where would he start today.3 ask what markets he likes now and why.4 ask for 1 book he thinks you should read.

If say the average for duplex's and triplex's in similar age, location, etc are 35k/unit then that could be a very rough estimation of the 4plex you are looking at.Finally, for my location, I would look at the tax assessment and make sure I'm not paying way over that amount.