Is 有方 an abbreviation of 有方法？ I hadn't heard 有方 before. I was surprised to find it means 'competent'.

A basic meaning of '方' is 'square'.

Is this '方' actually 方法，方式？ Could I change '方' for '方式' in '他领导有方'?
Yes 方 means 方法 (method) here, and 有方 means (do something) with the proper method/in the right way, i.e. competent.


  [with the proper method]∶得法
  领导有方