1. The PicoTurbo case was actually a loss for ARM. PicoTurbo showed the holes in ARM's patents (specifically prior art and the ability to implement patented functionality differently). ARM paid PicoTurbo millions of dollars to go away.
2. It is important to understand that interfaces (i.e., the instruction set) are not covered under patents or copyrights. ARM patents specific implementations of features mandated by the instruction set; that is how they protect themselves. It is legal to implement the latest ARM instruction set using techniques not covered by ARM's patents.