You can get a moisture alarm that will go off when a sump pump fails.

For a septic you can have a simple system with no mechanicals or a more complex system with a pump to the leach field and alarms for the system not functioning. 

Sounds like a bad idea; imagine what happens when your car is broken into and the thief finds those keys ... jackpot!

I thought about getting headphones but if they cancel out sound, they may prevent me from hearing a sound that I need to hear in the middle of the night or in an emergency like my bell, a smoke alarm or my cell phone etc.

As Kyle stated it varies by state and local jurisdictions but here is what the 2012 international residential code says(1 & 2 family dwellings)Article R315.1 Carbon Monoxide alarms.

We have several student rentals and while these kids are all going to university to learn, most of them also need a course in household 101  {We have actually had a tenant call us when the fire alarm went off rather than the fire department ... and that was after she tried to reach her mother}

We JUST moved in, we have ten months left, and I'm frankly, kind of alarmed that a real estate company thought it was okay to not only just come into our house with no warning, but to think they had any right to demand information out of us. 

Electrical, plumbing, HVAC, Termite Plates on the piers, wired fire alarms / smoke detectors, new breaker panel, arc fault breakers for all bedrooms and common areas, ground fault breakers for all wet areas ect. 

do you know how much on average property manager charge to run my rental is quadplex property Now i realized being a landlord is not fun at all so much unexpected problems and i just got a letter from the fire department about alarm and fire extinguisher so much headache .

I however bought a 2013 Ford Fiesta in 2013. it was like $13K brand new, but its manual transmission, manual windows, no CD player, no alarm, no automatic locks etc.