For single-family rental homes, is it normal to have a waiting period of a few years before cash-flowing? 

Best for singles, but I know couples who do this successfully and enjoy meeting new STR guests.

Your PM fees will also be less per unit for a multi unit vs single family.Tenants in multi unit buildings share walls so there is always the potential for noise complaints and neighbors that simply can't get along with each other.If you run into financial difficulties, it is much easier to sell off one or two SFRs than it is to sell one big multi unit.Traditional lending is much easier right now for SFRs vs multi units.  

I get business ideas from TikTok sometimes...)Connect on LinkedIn with all your personal contacts and professional contacts by going through your phone and email contacts list and literally connecting with every single person.

Are there any recommendations for a solid single resource to give a collective overview of home system life spans to support life cycle planning?

U can keep trying but as stated your best bet is a financial ( cash partner) and then you have to talk them into why they should give up a bunch of the deal to you.

Also I am looking for an experienced realtor on Oahu that has worked with investors and understand the investor mindset.Type of house hacking strategies I am considering:Multiple units (duplex, multi family home)Single home with roommates (rent out extra bedrooms)Single home with vacation rental (Airbnb extra bedrooms)And here are my criteria:Budget 60-75k downpaymentEastern windward side of Oahu (Kailua and surrounding neighborhoods)Renter or vacation goer friendly locationLightweight rehab (no fixer)Aloha!

Meaning you would be responsible for the studs in only or is the property insured like a typical single family home?

Look for appreciating properties, which to me are usually single families. 

Proximity to Lake Tahoe:- Around 15 million people visit Lake Tahoe every single year. - Reno/Sparks/Carson City/Gardnerville parallels the entire lake, and is only about a 30-45 min drive.