If landlord offered the extension of lease via text and we agree to stay another year, is it a valid and legal?

Interpretations of contracts usually requires examining the actual documents. An offer and an acceptance can constitute a binding agreement.

I filed an exporte restraining order on 16 year old son’s father , notice of only 8 days away. ? What if I can’t serve him

See https://www.washingtonlawhelp.org/issues/family-law

Can my tenants, who live in the same building as me, but with a different legal address, accept process servers papers?

RCW 4.28.080 describes service of a Summons. http://app.leg.wa.gov/RCW/default.aspx?cite=4.28.080. Suits for invasion of privacy usually depend...

If some lots in an association signed an Agreement to pay Dues & the Board failed to charge them, can the debt be collected?

See http://app.leg.wa.gov/RCW/default.aspx?cite=64.38.

Can discovery be used in another suit?

Courts have discretion about the admissibility of documents. Sometimes it is necessary to provide sufficient indicia of authenticity. ...

See https://www.uscis.gov/working-united-states/students-and-exchange-visitors/students-and-employment

Maybe he should make an application with the ATF: https://www.atf.gov/

My son got married recently and moved to another country. Should I inform USCIS about the change of status?

The USCIS website says a change of address notification is required. https://www.uscis.gov/greencard/while-application-is-pending

See https://www.ssa.gov/planners/retire/whileworking.html.

What does this mean?

The government often does child support actions. See https://www.kingcounty.gov/depts/prosecutor/child-support.aspx. The second statement appears...