What a mess. To give you any input, an attorney would need to review the purchase agreement, any written communications (including e-mails), and spend some time with you getting the oral communications into context. It could be that you can avoid proceeding based on a failed contingency, and then go find a different realtor (though for that you'd have to produce the listing agreement). Feel free to contact me for an initial consultation.
Take a look at items D and J on their disclosure form. Disclosing the waterproofing is one thing, and disclosing the need for it (water intrusion, flooding) is another. More information is needed to determine the nature of the remedies that may be available to you. Please feel free to contact me to discuss this.
Feel free to contact me if you'd like to discuss this. I suggest keeping very good written records of each event. Contacting the police will get the criminal side of the justice system involved, and filing suit will get the civil side involved. There may also be a "political" solution involving the suspect's parents. And, you may be able to do more to protect your property (fencing, dogs) and gather evidence (cameras, video, audio).
Ms. Sargeant has some very good ideas. The other issue is trying to convince your neighbor that you are correct. I imagine that you could show the survey to the neighbor, and he will still persist. In that case, you have legal options, but, due to the expense, a letter or call from an attorney may be the best route. In any event, more information is needed. Please feel free to contact me for an initial consultation. If we cannot help you, I can find someone who can.
More information is needed, including a careful review of the disclosure form and the contract. Feel free to contact me for a free initial consultation. You have to be very careful in assessing fault. It sounds like the inspector did his/her job (the inspection agreements tend to have liability caps) but that the seller both concealed information and gave false information. Realtors have obligations as well.
It may be as simple as having a lawyer send them a letter pointing out the problem and threatening legal action if the lien is not moved. They may not be happy because the lien may be invalid, but that is not your problem. Feel free to contact me to discuss this in more detail.
Mr. Gallick is right--you have to review the contract. It could also say if any lawsuit has to be filed in the California state court, or in a Federal Court here or there. It is possible that you could sue in Cincinnati, but that would depend on the terms of the agreement. I'm licensed in CA and OH, so I may be able to help. Or, I can help you find someone in CA. Feel free to contact me for an initial free consultation.
The facts could give rise to a claim for trespass, which in some instances allows for recovery of attorneys fees and punitive damages. It is hard to say from what you provide if that will be the case here. More information is needed. Compensatory damages may include cost to remove the stumps, replace the trees, plus the diminished value of the property. Again, more must be known in order to provide a better assessment. Feel free to contact me if you like.