more help

Okay, so after multiple suggestions, I've decided to get an exercise ball. However, I do not do well with options, especially when they're options I don't have the knowledge to judge between, especially not right now when I am ALL STRESS. So...how do I choose between the eighty different brands and sizes and varieties? I'm 5'3" and I'd like a ball with a weight limit of no less than 300 pounds (I'm currently hovering around 245 and really don't need to be worrying if it's going to burst under me). Also, how do you inflate them? Will I need a pump of some kind?

(One day I will learn how to do something new without making the internet help me step by step, but clearly today is not that day.)