Any return on zero spent is infinite and it doesn't get any better than that. 

For example, tell them I want the inside of the cabinets cleaned, well the bottom shelf isn't the whole of the "inside of the cabinets" -- there's 2 other shelves!

First off, I want to express my infinite gratitude for biggerpockets, this site has completely revolutionized RE investing and has made my investing experience so much easier.

I had the same idea of vacation rental for a property in Kachina (15 miles closer to town than Munds) and I passed on it due to the almost infinite number of choices available online.

I personally find the Series LLC to be a great tool for the individual investor who is planning to expand their operation, as it allows for you to scale infinitely - check out this article to learn more.

If you're willing to be nomadic, you can house-hack your way to an infinite number of Fannie Mae or Freddie Mac loans. 

While I’m still getting my head around this concept, the 3rd option is to cash out my retirement and place it into a Whole Life Insurance vehicle (infinite banking concept) to take loans against it for around 5% for real estate investments while the policy accuses/compounds over time, ie. 5 years (super simplistic for the purposes here).

You can get them off the shelf at Lowes for a couple grand or less....

Therefor, I don't think you can give any general ranges for any of these items.It also depends on the quality of the item that was installed in the first place...and who did the installation.On top of that, items like furnaces, which demand maintenance (changing filters regularly) will have a shorter "shelf life" in rentals since tenants are notorious for not maintaining them. 

They are supposed to last for 3-4 years in smoke detectors and have a shelf life of up to ten years, which is meaningful since these detectors do not drain the battery until water completes the circuit.