A defendent has the right of confrontation. Which means they have the right to cross examine any witnesses against them. If the alleged victim does not show up, the state cannot use their statements unless the defendant can cross examine them. In short, the State cannot make a case without the victim present in court. However, the state could seek a material witness warrant to secure the witnesses presence. However, most prosecutors will not go this far.
On the other hand, if the alleged...
You should get a lawyer. You might be able to compromise the theft, which requires you to pay money and get a release from the other party. Or my might enter into a CFD or and SOC, which gives you a chance to get this off your record.
It sounds like you either blew above a .15 or refused the test. When the judge enters a "no test" its really geared for DOL. If this was your first offense, you would only be suspended for 90 days, if it was a no test. If you were convicted of a refusal you would be suspended for 2 years or if you were convicted of a BAC .15 or above, you would face a 1 year suspension. This also changed the sentence and fines.
First of all you don't have to tell any cop that you have an arrest record. You don't have to talk to a cop in the first place. Secondly, you don't have an arrest record, since you were never arrested.
No Seatbelt tickets are non-moving violations. These do not affect your insurace rates or even go on your drivers abstract. In Washington, you can defer one Non-moving and Moving violation every seven years. I think the court is incorrect. You should be able to defer it.
I think the WSP is pulling your leg. I find it highly unlikely that cop even has a photo or that he had time to review before pulling your over. In my experience, these cameras are just observation ones and do not record. Usually cameras at intersections are photo red and they do not have the resolution detail to see a seatbelt violation.