On the PGA Tour it is what ever the amount the player works out with his caddy as an employee, plus expenses. Normally 10% of the players purse if he wins or what ever they work out. 10% of a winning purse is the norm though.
Depends on the individual deal they have with their player. Some get extra when they are part of a win at the 4 majors.
Do you mean caddy? If so, I believe it is between the player and the caddy
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