This mission is essentially just a set piece, single act mission. It has no enemies or civilians, only Lenny Dexter as a target. Killing him is optional, but leaving him alive leads to some extra dialogue at the after mission screen. Either way, the rest of the game is unaffected by your actions here.
There are various weapons available throughout the level, including a small arsenal in the trunk of the car and a number of melee weapons scattered all over the area. Some explosive barrels can also be shot, and either used to kill Lenny, or just to create an explosion, don't blow yourself up though, or you will get another special scene for this mission.
Shooting all the vultures in this level activates an Easter Egg. An ice cream truck appears, and runs over Lenny. Agent 47 can also die to the truck if he isn't careful, although it doesn't actively try to hit him. Getting killed here is almost impossible unless the players kill themselves intentionally.