What are the rules on paying players, contracts and transfer fees?

From the SARU Player Status, Player Contracts and Player Movement Regulations:

• A player may receive a material benefit (money, gifts or other benefits for playing) from a province or club. Genuine reimbursement of reasonable travel, accommodation and subsistence costs is not a material benefit. A province may regulate what its clubs pay players.
• A player receiving a material benefit from a club should have a written contract with that club.
• No club or province may sign a written agreement with a player under 18.
• A player contracted to a province must be registered with a club in the province they play for.
• Transfer fees for a contract player are agreed between the clubs or provinces. Unless they agree otherwise, the player may not be registered with, or take part in matches or practices for, the new province until the agreed fee has been paid in full.
• The current province may refuse a clearance if a contract player has not met their contract obligations, for example a duty to play for the club or province until after the intended transfer date.