I'm glad you're looking into everything before bringing your cat home...You're already off to a good start at being a great owner by taking the time to really know what you're getting into.
First off, I have never personally owned a long haired cat. I own three short haired cats (2 with very short, close hair and one with a fluffier undercoat and standard length hair) but, my sister-in-law's cat, puffy, a semi long hair (her hair is about 2,1/2 inches long) did stay with us for a while...
They all seem to shed at about the same rate...the cats with more undercoat (the softer shorter hairs) tended to shed more cottony hair that was more likely to "stick" to things, but all of the cats shed about the same amount of the outter guard hairs. Puffy's hair, because it was longer, was more visible (it is also white, so stands out like crazy on any dark surface).
Cats also "blow" their coat in the beginning of summer, and so at that time, you'll be able to get fists full of hair off a cat each day...Other than that time period (about 4 weeks long), the shedding is less so, and you can get by with weekly brushings.
The "rex" breeds of cats, those with curly hair, shed very little or none (kinda like poodles), so those might be a consideration if you really don't want to have to deal with loose hair everywhere.
I think, more important than the amount of shedding, is how much time you really want to spend grooming (in terms of choosing what hair length to look for in a cat). Although the short hairs might shed as much as a long hair, they can go without brushing if necessary, but with a longhair, you'll have to brush at least 2-3 times a week (in most cases) to prevent matts from forming.
In the end, if you are committed to grooming and feeding a good diet (many times cat at the shelter will have horrible coats with dry loose hair from the low quality food they get, but will improve when you get them on a good steady diet), you'll have far less shedding no matter what coat length you choose.
You might want to consider the hair color though, in terms of it showing up everywhere...puffy's white hairs and my red tabbie's hairs show up much more than the hairs shed by my standard brown tabby and my black cat.