If you want the original marker lights in the front to also function as turn signals you will need to install a different socket in the lights--one that will accept an 1157 amber bulb. This is not hard to do.
The tail lights will also have to be dual filament bulbs (1157). The turn signal will have to be a 7 wire (Signalstat 900) in order to have the turn signals and brake lights using the same bulbs in the back. A four wire turn signal switch will require separate brake lights on the back--a four wire signal flasher will not handle brake lights.
Usually, if you have lights coming on when they are not supposed to or if some are dim when they are not supposed to be, a bad ground is the culprit. The exact location of the bad ground is sometimes hard to track down, but just think of the quality time you can spend on your truck just looking for bad grounds
