I’ve had from 1 to 4 cats most of the past 40 years.
Nowadays I live in a townhouse complex. If you love your cats, my recommendation is to keep them indoors. My cats never go outside except in a carrier. They shy away when I open the door to the outside. They are sometimes curious, but won’t step outside. The hazards of outdoor living can be injurious or fatal. Indoor cats don’t get fleas unless you bring them in on your shoes or clothes.
By 9 months of age, unless they have been in an environment without a litter box, they are probably already litter trained. Scratch and bury is instinctive. If two cats and one litter box, expect to scoop or otherwise clean the litter box about 6 times daily; more if needed. The recommendation is one litter box per cat; not because cats are territorial, but so the litter doesn’t become too soiled between cleanings. Let it get too messy and you might not like their alternate choice. I have 3 cats and 3 litter boxes at this time. One of the cats will lead me to a soiled litter box.
Most cats love kitty treats. Makes it easy to teach them their names.
They love to play with toys. Small balls or things they can bat around the floor, or things that dangle from a stick. Paper wads. One of my cats brings me a piece of rope and lays it across my lap, my arms or the keyboard to play with when she thinks I’ve sitting at the computer too long. Most will chase a laser dot until they drop.
They love attention, kittens love to play. All ages pay close attention to your voice and movements. While cats have a reputation for being aloof, they do develop attachments. Trust is important. They appreciate coming home from the vet’s alive.
The initial vet exam is important to assure that they are healthy.
IMO, the riskiest of the insidious health problems is urethral obstruction. Neither gender is immune. If one can’t pee, take it to the vet’s immediately.
My cats have been strays or have come from an animal shelter. The shelter policy nowadays is that their cats are “fixed” and vaccinated upon adoption. My youngest was about 2 weeks, presumably abandoned by the mama cat. We bottle fed her for weeks. Turned into a great daddy’s cat.
Unlike @Mittineague, I’ve never met a cat who understood “No.” Mine seem to think that means “wait until the human isn’t looking.” I don’t think I tell anyone “No” any more. I just find an alternate toy for them to play with. If you’re a cat, everything is a toy.
I’ve has some cats who were declawed, but most not. I prefer not. Scratching posts or pads work very nicely. Claws can be carefully clipped if necessary. Some cats are incredibly gentle about touching skin with claws, others are not.
I’ve never had a cat live as long as @mawburn’s. My oldest cats lived about 13 years.
Oh, Yes!, ditto @chrisofarabia’s comment… they DO love paper bags and boxes… especially boxes.