Here is a picture of a rotti that we board. Obviously he is a sweetheart and loves to play with my cavalier.
They can be trained for just about anything -if 'they get it'. For herding you are best with a working dog e.g. border collie, heeler, corgi, etc.
No, never had fainters -they'd always be stiff because of all the excitement of dogs coming/going at the kennel. LOL