Conducting business in OR and WA
1. Do we need to register in Washington as well as Oregan?
2. Plan to work in CA. What procedure do we need to follow?
To answer your question its important to understand the nature of your business.
Technically, if your business has physical presence in another state you should register it there as a foreign entity. Having an office is an example of such physical presence.
With that being said, having a job in a different state might or might not be considered as physical presence in the state. So to further help you I would need to know what kind of work you do, what is the duration, and how many such jobs do you expect to have in each of those states.