How to toggle to camera view via python? Is there a way to programmatically achieve the same thing as pressing the 0 key the numpad?
The operator for switching the 3D view which is associated with numpad keys is view3d.viewnumpad().  You have to be in the right context (3d_view) to use it and select which view you want to set:

import bpy

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        override = bpy.context.copy()
        override['area'] = area
        bpy.ops.view3d.viewnumpad(override, type = 'CAMERA')
        break


Another way, without the operator would be:

import bpy

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        area.spaces[0].region_3d.view_perspective = 'CAMERA'
        break


Which is equivalent to: 

import bpy

area = next(area for area in bpy.context.screen.areas if area.type == 'VIEW_3D')
area.spaces[0].region_3d.view_perspective = 'CAMERA'


Other options are  [‘PERSP’, ‘ORTHO’, ‘CAMERA’]