Re: lifespan of engines
Yes, they can last quite awhile if taken care of properly.
I'd mix the fuel at 24:1 after break in unless you want to do a lot of plug changing and de-carboning.
Common wear items include rings (cheap, easy) chain/sprocket, also cheap and easy and maybe after 5-6000 miles a wrist pin bushing or bearing, depending on your engine. No biggie.