Coach / Athlete agreements

Hello forum wanting to hear from any career coaches or basically any coach who has agreements set in place with high profile athletes they coach on the following.

1 - % of income/prizemonies/sponsorships paid to the coach

2 - monthly payment prices for coaching for say 4 days per week.

3 - and has anyone had experiences in approaching this matter say 3-4 years into coaching an athlete.

the reason i have a triathlete who will next season take part in the very lucrative aust circuit and want to know how to approach this matter.