Many fitness skaters turn into speed skaters as their skills progress. Skating and training in groups is a lot more fun than slogging along on your own. Skaters skate in long pace-lines and take turns 'pulling' while others draft behind in the aerodynamic slipstream. Standard distances are 1,5,10 and 20 kilometers. A broken wrist will heal but brain damage is forever.
Cycling gloves are also a good idea.
Beginners and intermediate skaters should not even stand up on skates without a helmet, knee and elbow pads and wrist guards. Take a lesson, you'll be glad you did. The International In-Line Skating Association certifies instructors. Outdoor wheels tend to be 80 mm in diameter and have a hardness from 78 to 83 durometer. 3 or 5 bearings are common.