GP earned per match is around 20-80 gp + gp to repair gun
EXP earned per match is based on time spent playing in the game or amount of rounds played and total amount of kills and maybe something about deaths.
SnD takes a while since it's around 15+ minutes long for a 13 round match
TD is actually pretty fast if you never noticed.
EM can have many rounds so that is why it earns you good exp
Im not so sure about mutation mode though even if it has like 17 rounds. Ive never played 5 rounds or more of mm straight.