It seems to me that everything depends on the type of formations you are running. The size requirement for each player is pretty dynamic if you are playing a Jumping style offense (taller the better) versus a running in or crossing offense (small size and agility are best).

From what I understand, you put your strong dope at pivot and your playmaker at CB. The other backs at least must be tall for shooting over people but from what I understand, having height at the wings isn't a bad thing so long as they are agile as well. That being said, I'm not even considering playing my 208cm guy at wing.

In other words, I have no idea what I'm talking about because I had no idea how it was played until today. All I know is about what I've read.

ok basically i draw this conclusions from RL so dont take it as granted

first LW and LB need to be right handed, RW needs to be left handed otherwise its impossible for him to score, RB is better to be left handed but in RL if you dont have a good left hand player to play that you play a right handed one.

second: LB & RB & pivot need to be tall, no exceptions for that cause backs need to jump over defences the most and pivot needs to be a big guy to fight for his space. PM, GK and wingers can be either tall or short.
when defending you have few tactic, most used are the basic 6-0 meaning 6 people at the 6 meter line and none in front of them, its good to stack tall guys in the middle, put short ones on wings. second most used tactic is 5-1 which is 5 guys at the 6 meters line and one in front of them to try to intercept the ball or to get in the way of the shooters.

wingers = jumping, shooting, technique
backs = shooting, jumping, passing, technique
PM = playmaking, passing, technique, ball control, speed
pivot = strenght, off the ball, shooting
gk = one on one, reflexes

for defense
strenght, blocking, marking

stuff like agility and stamina are usefull for all