Where should I start with this situation?

There is a question at the end of this, but to what end. What do you want to accomp,ish?

Dangerous Trees and obnoxious neighbor...

You could File a nusience suit claiming the trees are a danger

Can I go to jail for failing my first urine test?

If the drug testing is part of your probation, then you could be show caused.

Can I be sued for damages if I were illegally evicted?

You could sue the roommate, but they could simply say they were letting you stay there, you refused to leave, so they changed the locks.

This is too speculative. You would need a paternity test to proof parentage and not a DNA test on ancestry.

When separated is it 6 months or 182 days?

By the time you file if you have a property setttlement agreement and no Kids it wint matter

How to prove during court ordered visitation with 3 year old the other party is talking badly?

You shouldn't want to have your three year old testify so unless someone else willing to testify overhears or otherwise observes the behavior there...

Do you were subpoenaed the you must appear in court if called, you must answer questions, unless the judge rules the question are irrelevant or...

There is no statute of limitations for a felony.

Virginia is an at will state. Meaning you can be fired for any reason not barred by federal or state law.