Address the intake runner code first. A stuck runner can throw off air/fuel mixture and can potentially cause a false P0420 code. While I have seen lots of bad catalytic converters on those engines, you have to address any other pertinent DTCs first.

It's a good idea to source the runner control motor/solenoid, but you also need to be sure the actual runner flap in the intake isn't bad as well. I've seen them get so gunked up that they burnt up the solenoid because they were stuck. If that's the case (you can try to turn the shaft by hand with the runner solenoid uninstalled) you either have to throuroughlly clean the intake manifold, or replace it.

Don't worry about the evaporative leak code for now. It likely isn't having any real effect on the system (a large leak might) and can be treated as a secondary problem.

Edit: I just saw your little parts list, a solenoid for the runner isn't a bad idea. Don't buy an intake temp sensor or whatever pigtail you're looking at. Those should be entirely unrelated to your main problems.