[farm rat]

Trickle charging is just for maintaining the battery. Your battery is 4 years old and these cars rely on batteries much more than older cars due to the mass of electronics. Changing out the battery should not be a challenge if you are half way mechanically inclined. Be sure to clean the cables good and small amount of dielectric grease probably would not hurt. It will help keep the connections from corroding.

Basically the whole car is a ground. If you are charging the battery your charger should be hooked directly to the battery. If you are jump starting it there are jump start points under the hood, use those.