I have a cat - he's 16 1/2 now. I've had previous cats and had 2 cats at once.
If you aren't willing to take in 2 cats, don't. I don't know what shelter is saying that but no shelter that actually wants to adopt their pets would force that rule. Don't accept that and if they insist, go elsewhere. There is a difference in taking care of 1 versus 2 cats. Hopefully you get 2 that get along or leave each other alone but if you don't, you have to deal with the fighting and domineering they do. And you should have more litter boxes so that's hard in a small living space. Anyway, if you don't want two cats, don't do it.
Cats are nothing like dogs and if you happen to get one that is, that's a longshot so don't count on it.
Cats pretty much take care of themselves and that's one thing I love about them. I would suggest declawing your cats if you care about your carpet and furniture. I didn't declaw my current cat and he's destroyed quite a bit of carpet (not his fault, he just likes to sharpen his claws).
Cats barely make any noise - at least noise that can be heard from outside your living area. They are a little creepy that way too
Start at the get go on whether the cat can sleep with you. My cat does sleep with me and I've woken with cat fur in my mouth or scratches on my arms and face because he's stretching all night long. And he snores

So if you don't want them in your bed, establish right away where they will sleep.
Thanks for posting this. People are so freaky about dogs that it is nice to hear that someone wants a cat.