If someone is charging they should be able to put in writing what it includes and itemize.
This includes stuff, like membership fees (which all have forms, and time periods ), coaching fees and such.
There are guidelines, recommendations and allowances.
Regarding USAG membership. It is yearly, the card comes to your address with your gymnasts name and number. There a lower introductory fee for a first time gymnast (again there are guidelines). And then the full athlete rate. If there is more I am sure it is spelled out.
JO or Xcel doesn't matter, one yearly fee. Now might be different if you join mid year or move to L3 mid year, but that would be a one time thing.