How much of the stated returns go to parties other than the investing client? I have seen fees for traders and intermediaries mentioned. Just wondering when/how those fees are paid.

None of that goes to others.  Please confirm this when you see the contract, but normally the return quoted is NET to the client.  That is the normal protocol when quoting returns.  Platforms nearly always quote client returns as “net”.  Fees and percentages to other parties come out of the gross, above and beyond the net.