How do you earn medals? How much XP do they give?
The medals are just for the first, second, and third place for each category (Eliminations, Objective Kills, Objective Time, Damage Done, and Healing Done) other than Deaths on your team. The bonus XP is 50 for a bronze medal, 100 for a silver medal, and 150 for a gold medal. Note that you can only receive a single bonus, matching your most valuable medal.