My first cat? need some help deciding.?

well i need some help makeing a few descions and i need your help and tips. i just convinced my parents to allow me to get a cat. im more of a dog person but i dont mind. the only pets that i have ever owned are goldfish and a bird. now i good friend who has 3 cats and they are very friendly .i have also had some experience with some crazy vicous cats. now i need to make sure that im ready for a cat. by answering thses few basic questions. once i by a kitten what type of needles or medication do they need? boy or girl cat which is easier and more playfull? if a cat bites or scratches can it infect me in any way ? and lastly the whole cats peeing other places then there litter box. do i need to get my cat neutered , or will it stop the cat from peeing every where?. thanks for any help.