There is no reciprocity between WA and OR for CPL/CWP. Therefore your OR status is irrelevant while in WA.
The basics are:
-WA. has pre-emptive gun laws, the state law rules, no local ordinances can be more restrictive.
-Open carry of a loaded firearm is legal.
-NO loaded handgun in a car unless you have a valid CPL (WA., or one it recognizes).
*NOTE* "Loaded" by WA law means a round physically in the gun, regardless of whether it is chambered, the correct ammo, or even could be chambered. If you place a loose .500S&W cartridge in the mag well of a Ruger LCP, it is a "Loaded" gun under WA law.
-Gun and ammo can be in proximity, and in same area of car (no requirement to keep separate).
-If gun is in unattended vehicle, the vehicle needs to be locked and gun must be concealed from view.
RCW 9.41.270 talks about carrying weapons capable of producing bodily harm.
RCW 9.41.300 will tell you where you can't carry per state law.
All of the main laws can be found here: http://apps.leg.wa.gov/Rcw/default.aspx?cite=9.41