As an American/British Dual National does my criminal history follow me into other countries?

See https://www.courts.wa.gov/newsinfo/index.cfm?fa=newsinfo.displayContent&theFile=content/guideToCrimHistoryRecords

Moving with child to different state does the court needs to be notified or notifying non custodian parent will work?

You should follow the court ordered parenting plan. It may be possible for your to ask the court to modify the order considering your substantial...

Filed for divorce jointly. Trying to fill out the financial assets and liability form in WA. Need help!

You should retain an attorney. See https://app.leg.wa.gov/RCW/default.aspx?cite=26.16

How do i address the issues of ex leaving state after divorce and quits paying his support payments/ to his disabled ex wife?

Courts rarely act on what somebody heard somebody else may or may not have said.

The use of the word "may" means they have the option, but are not required. You can hire a lawyer to go after the entire amount.

There are statutes describing the crimes of kidnapping and custodial interference. https://app.leg.wa.gov/RCW/default.aspx?cite=9A.40 Write...

Is it against the law for a 17 year old to date a 24 year and have sex with them with a another person under the age of 18 ?

RCW 9A.44 addresses sex offenses. https://app.leg.wa.gov/RCW/default.aspx?cite=9A.44

Can Ex use my motion for back child support to claim his own charges from me? WA state/Snohomish County

Judges have great discretion about what to admit in evidence. http://www.courts.wa.gov/court_rules/?fa=court_rules.list&group=ga&set=ER

How can I request my wife to attend the trial for divorce personally instead of just sending her lawyer to the court ?

Your lawyer or the judge can issue a subpoena. CR 45 http://www.courts.wa.gov/court_rules/?fa=court_rules.list&group=sup&set=CR

Can Facebook messages be used as evidence?

Judges have considerable discretion about what to allow into evidence. http://www.courts.wa.gov/court_rules/?fa=court_rules.list&group=ga&set=ER