How and what should I do?

If the tree was on your property then it was trespassing and theft/ conversion on these facts. Get a tree expert to give you a value for the tree...

Can I take possession of the vehicle and sell it?

On these facts you should be able to sell the vehicle - especially so if there is no equity in the vehicle and you are merely mitigating expenses....

If I remarry and my husband is a veteran and he had a first wife, what happens if he dies?

Sounds like you might want to go sit down with an attorney and draw up prenuptial agreements and possibly update your will.

I have court orders in one county, and the other party moved to a different county. Can I transfer my case to the other county?

Possible. Not as simple as filing out a request form. Best to consult with an attorney to develop a strategy.

[Please HELP] The towing damaged my new car.

Most likely you have "full coverage" insurance. Use it. Your carrier will deal with subrogation of the claim plus your deductible.

Without the financial means to hire an attorney, how can I get non-custodial to exercise his rights for visitation?

Visitation is a right, not an obligation - you can't force the other parent to take a more active role.

If we divorce. Does he have any rights to the house?

It should be your separate property but it will be your burden to prove it. A pre-nup would have gone a long way.

Can i sue the insurer of the vehicle and /or his insurance company based on the fact that he had the vehicle insured on his name

Sounds like your action is against the negligent driver. You have not listed any facts that give you a cause of action against another party's...

Do I need to go back to California for any trial for this case? Who's pay for airfare ticket & other expenses?

Best for you to hire a CA attorney to review the case and advise you. This is not a simple issue for a public forum.

Mediation is a confidential proceeding. This sounds a lot like the other party is toying with you.