Get a lawyer and keep it off your record.

What should i be aware of

You will get another court date. You can get an appointed lawyer.

What will happen if I get pulled over in Missouri for speeding or something?

Unlikely they will extradite you. However, if you get pulled over you will get detained. Also, Washington may suspend your driver's license, and...

Will my husband have to do the manditory 85%

Yes it's 85%. I have no idea why he'd get double credit for county jail time.

Does an SIS (suspended imposition of sentence) become a closed record for the public?

Yes, it's a closed record as your guilty plea was withdrawn.

Was this detainment situation legal?

It depends on the facts of the arrest of the friend. Find a civil rights attorney to discuss it in person.

Would a phone call to the treatment center by his lawyer make a difference?

We need more details. If he voluntarily went to treatment, it's up to Tom to send proof to his lawyer or the court.

When is the soonest I can possibly be released from probation?

You will likely be eligible after half of your probation has expired, so long as you have no violations. You don't have to apply. Talk to your PO...

Will I be able to get this charge dropped down to a lower charge or it possibly dismissed since the balance will be paid?

You won't get it dismissed unless you pay the money back first.

Do I come clean or hope I am clean. And possibly outcomes of either one

Normally I recommend being honest. If you're clean, you've earned some trust, if you're dirty you've earned some trust.