You will need to place a claim against the at-fault party's property damage liability policy. It will then depend upon the limits of the driver's PD policy and the investigation of the claims department of his insurer to decide how much they will pay out on a claim for the damages the drunk driver caused to your brick wall and trees.
Once you make a claim through the property damage liability portion of the at-fault driver's policy then a claims adjuster from his insurance carrier should come out to survey the damage. The adjuster should be able to give you information on what they will pay out on according to the terms of the at-fault party's policy coverages and state laws, if they have a bearing on your claims filing.
The claims adjuster for the at-fault party should be able to answer more of your questions about what they will do concerning the repair of your brick wall and your trees that were damaged. If you need to get consumer advice on what your rights are according to your state's laws contact your state's insurance regulatory body.