Rather than waste your money on a bunch of CO detectors, couldn't you just leave the windows open?? Cross ventilation should remove the carbon monoxide

CO detectors are probably cheaper than trying to heat the outside.

You'd think so, but unfortunately it doesn't. CO concentrations can (i.e. have been shown to) rise to lethal levels in spite of major passive and/or cross-ventilation... much better to use a CO detector and be sure.

OK last night I discovered two new things about the place

One is the washer hookup does not drain, or does not drain fast enough, which left about a washer's full of wash and rinse water on the basement floor.

Two is the dishwasher was never actually hooked up to water.

I won't mention to the management company that hot and cold is reversed on two out of the three places it is dispensed. I find that part funny. But certainly it was some plumber's amateur hour out here, and damage has been done.

My dad's washer did that for two decades, though it leaked somewhat less water than that. His solution was that we were always to put a bunch of towels on the floor whenever we did laundry. I recommend you don't go that route, your kids will think you're cheap and lazy.

Hmmm but that makes me think... if I need to, I could drain the washer into a greywater holding tank of some fashion, and then siphon it outside. Or even carry it outside. This is only possible because it's a newfangled high efficiency washer which uses less water. Bosch, you know the Germans make good stuff.

On the dishwasher, I notice that the parts to actually hook it up are sitting under the sink. :D I also notice that it was never bolted in. Amateur hour.

Time to freak out on the management company.

Yeah. Better to complain about a laundry list of items now than a slow drip of problems over time. (See what I did there?) If you wait, then they will think you broke the stuff after living with everything being fine initially.

I don't freak out on anybody!

Oh, it's not just the washer drain having a hard time draining... it's the entire house! After blocking off the washer drain, the morning shower overfilled the kitchen sink.

What. The. Fuck.

It would take an amateur a lot longer than an hour to fuck up the plumbing to this degree. I think you're dealing with a serious DIYer.

As a dedicated DIYer, you have my sympathies.

I also agree that you should make a list of these major items and present them earlier rather than later, and press for some kind of inspection/baseline/checklist etc.

Good luck man.

Does the toilet flush into the kitchen sink too?

Sounds like there might be roots growing into the sewer pipe outside. A good plumber will be able to identify the problem. It may require a visit from roto-rooter.

Speaking as someone who has never owned a house in her life, and for whom renting is the norm: totally do this. It is an absolute must do. The fact that the management company hasn't already done this with you is quite poor practice, but some are hotter on that stuff than others. If you don't then it is your word against theirs should any of this stuff prove awkward.