I highly doubt it is if they are only touching your property.
Is it legal to hit someone on your property. Whether you will actually be held liable depends on how the person was injured and what their status was on your property. As the owner of the servient tenement you must not interfere with or restrict these rights. You are well within your rights to sue someone if they punched you.
Nuisance also comes under common law. In many states in the USA a person can use lethal force to protect their family and home without facing legal prosecution. You cannot hit someone with a baseball bat or any other weapon just because they are standing in your.
If the ball keeps hitting the roof at all hours of the night then it would be trespassing each time but would be actionable as a nuisance. It doesnt matter if its road rage an aggressive neighbor dispute or some other situation. A party who is lawfully authorised to benefit from an easement such as the neighbour with a right to use your driveway to access his or her property and who uses the easement in the prescribed manner will not be liable for trespass.
If you think someone else is responsible liable for the accident you can make a claim against them for any damage to your vehicle or property. Intentional damage to your property isnt just unacceptable its illegal. If you were just pushing them as part of an argument or an attempt to intimidate rather than push them off your.
If a guest customer or trespasser is injured while on your property they may be able to bring a personal injury lawsuit against you. It is an offence to leave the scene of a vehicle accident without doing this. I think in most countries certainly including England where I live it is legal to hit someone if necessary to stop them beating someone up although it would depend on the circumstances.
If your car can be repaired you should get a written quote from qualified repairers for both labour and parts to repair the vehicle. This is called the Castle Doctrine. Have attempted a citizens arrest.