I would just treat it like any other utility, cable provider or alarm monitoring.  

is there any case where 'old' smoke/CO alarms are still 'grandfathered'?

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. 

The only issue seems to be the income and you do not seemed alarmed that she will not be able to pay.Why don't you just take 2 months security instead of a whole year in advance and keep the rent at $1100? 

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}

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.

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

It's what I have observed ...There are a few alarming statements in this forum, but it may just be due to jurisdictional differences.

Most alarming is clear sign of unauthorized occupant.The tenant is a single mom with her 3 young kids.

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