Django - Consulta sobre ForeignKey soy nuevo urgente...

from django.db import models

from apps.faena.models import Faena

from apps.producto.models import Producto

from apps.cliente.models import Cliente

from apps.contratista.models import Contratista

from apps.contratista.models import Transporte

from apps.contratista.models import Chofer

from apps.contratista.models import Vehiculo

from apps.contratista.models import Carguio

from apps.contratista.models import AdmDesp

from apps.comercial.models import Comercial

# Create your models here.

class CuadroControl(models.Model):

   class Meta:

   db_table = "cuadrocontrol"

   id_cuadrocontrol = models.AutoField(primary_key=True)

   ts_cuadrocontrol = models.DateTimeField(auto_now_add=True, blank=True)

   faena = models.ForeignKey(Faena)

   fecha_guia= models.DateTimeField(auto_now_add=False, blank=True)

   numero_guia= models.IntegerField(verbose_name='Numero de Guia', blank=True)

   imagen_guia= models.FileField(verbose_name='Imagen de Guia', upload_to='guia/%Y/%m/%d/', blank=True)

   transporte= models.ForeignKey(Transporte)

   chofer= models.ForeignKey(Chofer)

   patente= models.ForeignKey(Vehiculo)

   factor_unitario_transporte= models.IntegerField(verbose_name='Factor Transporte', blank=True)

   neto_transporte= models.IntegerField(verbose_name='Neto Transporte', blank=True)

  def __str__(self): # __unicode__ on Python 2

     return self.id_cuadrocontrol

from django.db import models

from apps.faena.models import Faena

# Create your models here.

class Contratista(models.Model):

    class Meta:

        db_table = "contratista"

    id_contratista = models.AutoField(primary_key=True)

    ts_contratista= models.DateTimeField(auto_now_add=True, blank=True)

    rut_contratista = models.CharField(verbose_name='Rut', max_length=10, blank=True)

    nombre_contratista = models.CharField(verbose_name='Razon Social',max_length=200, blank=True)

    factor_contratista = models.FloatField(verbose_name='Factor',null=True, blank=True, default=None)

    faena = models.ManyToManyField(Faena)

    activo_contratista = models.BooleanField(default=True)

    def __str__(self):              # __unicode__ on Python 2

        return self.nombre_contratista

# Create your models here.

class Transporte(models.Model):

    class Meta:

        db_table = "transporte"

    id_transporte = models.AutoField(primary_key=True)

    ts_transporte = models.DateTimeField(auto_now_add=True, blank=True)

    rut_transporte = models.CharField(verbose_name='Rut', max_length=10, blank=True)

    nombre_transporte = models.CharField(verbose_name='Razon Social Transporte',max_length=200, blank=True)

    factor_transporte = models.FloatField(verbose_name='Factor',null=True, blank=True, default=None)

    faena = models.ManyToManyField(Faena)

    activo_transporte = models.BooleanField(default=True)

    def __str__(self):              # __unicode__ on Python 2

        return self.nombre_transporte