“don’t even know if allergic to them” Typically a humane society will let you play with or interact with some cats before adopting them, do that or go to a cat cafe first, you don’t want to be finding out after getting a cat that you’re allergic… Best way to tell is put nose to fur coat and inhale.
I’ve owned 4 different cats in my adult life and we had two when I was a kid (not at the same time). They will each have their own personality, some will prefer more interaction than others. Some will be more violent than others (don’t play with them with your hands it can encourage biting or scratching people, always use a toy)
You will want cat scratching poles for the cat to use instead of your furniture some flower varieties have pollen that is toxic to cats (lilies or pretty much any bulb) the cat just has to smell it, not eat it, to get sick (or worse). And be aware that you will likely want to trim the cat’s claws, that involves holding the cat snugly enough for them to not escape while trimming their talons. Older cats may have medicine you’ll need to give, so definitely don’t be shy about thrusting a pill down their throat if need be.
Cats can be perfectly fine as an only cat, but it will help to find toys that encourage solo play, one example is a circular plastic track with a ball in it that they can hit around and around.
Also, be aware that hairballs are a thing and can be a common occurrence (weekly, sometimes more often) there are strategies such as a furminator comb (removes excess hair by brushing), hairball diet cat food, hairball treatment goop (comes in a tube and they have to eat a little bit).
And of course, cats need to exercise and watch their diet just like humans, and they’re creatures of habit so you will want to not get up early to feed or give them treats because they will expect that at that time then.
Oh and being woken up at strange hours of the night is a normal occurrence whether it’s from knocking shit down in the other room or just sitting on your chest and meowing.
All these people saying two… Realize that it depends on the cat’s personality, I’ve had a cat that would go for blood with any other cat, very territorial, so don’t try to just get two cats if you don’t know that they’ll work well together. Last thing you want is them hurting each other while you’re at work.