I don't have the time do go indepth on using a ball. I will say that a speed ball mainly works your timing and muscular endurance of most of your arm muscles, mainly your shoulders and biceps. despite being called a speed ball... its not actually all that great for building up speed because there isn't alot of resistance there and you're using limited muscle.

Some people use gloves, some some wraps and some use nothing, your hitting a relativly soft ball and alot of techniques don't even involve striking it with your knuckles so I wouldn't worry to much...