He has asked;"Provide protection around water heater or furnace to prevent children from making contact with theseappliances."

However, such a provision doesn't actually prevent that additional/junior lien from attaching to the property, leaving the 1st lien lender stuck with the issues @Chris Seveney mentioned. 

Wynd detectors are usually good for air quality, their effectiveness specifically for detecting marijuana smoke can vary, as they aren’t designed solely for this purpose.

What prevents you from doing the same for real estate property taxes?

You would be a breath of fresh air.

Yes 2% and most of those are NOT reoffenders it is a simple thing of being a day late to reregister (and yes they will send you back if you are a day late) The whole registration thing has NEVER prevented a sex crime from happening.

I have my eye on a couple of small places that I am interested in for Air BnB.  

I think the expenses are light.If you want to achieve market rents, no central air is going to be an issue.

For example, you may build a house that costs $1 million to build, but once it is finished is immediately valued at $1.3 million, so you created 300k in equity out of thin air which you can use to borrow against.

Alternatively, you can offer more such as central air when the competition doesn't have it.Avoid areas with a lot of new rental deliveries.