I have tried both, I think it depends on the market you are targeting and the type of leads.

Is your DSCR ratio greater than 1-meaning are you cash flowing (according to the lender's criteria of mortgage, property taxes and insurance (and HOA) if applicable).

Whether you should take a retirement distribution or not depends on several factors1) How much do you value the freedom/flexibility to ues the money NOW compared to when you are 60 years old.2) What type of return can you get having cash vs investing in an IRA / SDIRA.If you can make a 1% - 2% better annual return in your personal name, it may make sense as the added return will pay for the penalties over a couple of years.I personally cashed out of my retirement account back in 2016 and it was the best decision I made.

Depending on what the potential jobs offer in terms of income, does this seem like a realistic strategy?

Prosper and Lending Club also offer peer 2 peer loans, usually up to $40-$50k depending on which company you look at.

AND, your son will be at the mercy of the SELLER and dependent on the SELLER's good choices for the life of the loan.

I’ve seen that in my W-2 job, so it makes sense that the same value is applicable in real estate.

This also helped us in an unattended way when investing with my Solo 401k because banks treated the funds as liquid when invested in a public traded exchange versus in their fund and helped with securing better commercial financing on a deal because of the strength of our application in liquid assets.

Damage to the garage, depending on how much and what it is, charge them and get it fixed. 

I invest in Boise, ID and do quite a few BRRRRs, LTRs and STRs- varying degrees of success depending on how much equity we can force and the type of back end financing we can find, but the tax benefits are great and it's a rapidly growing market and Idaho is probably the most landlord friendly state in the nation.