I'm 100% self taught through 30 Day Stay and learning from my peers and mentors in the space.

Are cold calling or broker relationships more effective?

That will likely be one of the side effects of improving your property and should be accounted for in your analysis.

I have heard vented units don't dry as effectively but haven't heard any complaints from my tenants and believe the technology continues to improve.

Prior to last year, effectively any SFR was eligible for a short term rental license.

These are leased to businesses (like chain stores) that cover taxes, insurance, and maintenance, making them much more hands-off than residential rentals.Real Estate Syndications / REITs – You can invest passively in commercial real estate (apartment complexes, self-storage, industrial, etc.) through syndications or real estate investment trusts (REITs) without being a landlord.Hard Money Lending / Private Lending – With $500K in equity, you could act as a private lender, funding real estate investors who flip homes or develop properties.

You can also check out a group on Facebook with other investor like your self called Yellowbird.

Part of the reason why the rehab was cost effective was because I have a long relationship with contractors, have experience, and I also give this contractor a lot of business.

I also self manage.  

However, if the FHA interest rate is lower, I would still go that route and if rates drop refinance  however keep in mind FHA has PMI for life  Here you go FHA has the self sustaining requirement that requires the three non owner occupied  units to cover the entire PITI which with 3.5% or 5% down is virtually impossible with today's interest rates and price level.