I had kind of the same thing happen, only it was with my hedgie Lily. She's my first personal pet, rather than a family pet. I did some research, mostly on the site of the breeder I was going to buy from (lucky all of her information was mostly up to date), but I know now I didn't do nearly enough. After I got her, I found this site, and started reading up more on equipment, food, and cages. Since then, her living area's been upgraded to a bigger cage, a wheel that's easier for me to clean (So that purchase was more for me than her, but she likes it!), a few different cat foods rather than the one hedgehog food I had (Spike's Delight), and a CHE set up, which makes it SO much easier to keep her cage warm. I'm just glad that none of my information was incorrect enough to cause her harm before I learned better. Like you, I've definitely learned my lesson as far as doing enough research before buying an animal. I've been wanting to get sugar gliders, but I know I don't have the money, time, or room to take care of them right, plus I'm a bit intimidated by the diet issues with them and what's best. I won't be getting them for a few years yet!
Also like you, I have a binder where I keep Lily's info, vet records, and a section with general hedgehog info in case I have to leave her with a sitter. I like this so much that I've decided I'll probably end up keeping something like this for most of my future pets!
My friends think I'm slightly insane, but...I've already accepted that I will be the Crazy Animal Lady when I get older, so I suppose I might as well embrace the role early!