The starting point position of what? The 3D model? If yes, you can just specify the coordinates when you display the shape with shape(s, x, y)
What do you mean by a “location that starts”? You want to animate the model?
Yes, you can take a look at the camera() function :
camera(eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ)
Sets the position of the camera through setting the eye position, the center of the scene, and which axis is facing upward.
Yeah sure, you need to use a separate PGraphics object where you are going to display your model.
From the documentation :
Use this class if you need to draw into an off-screen graphics buffer. A PGraphics object can be constructed with the createGraphics() function. The beginDraw() and endDraw() methods (see above example) are necessary to set up the buffer and to finalize it. The fields and methods for this class are extensive.
In order to have a 3D context for the PGraphics, you need to use P2D or P3D for the main window.
You use PGraphics the same way you use drawing commands in Processing but you need to prefix it with the name of the graphics instance (pg.drawingFunction(...))
So those are not related to what you described earlier with your picture, you need to use a PGraphics object in order to draw on a separate buffer isolated from the rest of your sketch.
You only need to use your instance of PGraphics in order to display what you want. You can still use global methods in order to load your OBJ file. (like you did in the code above)
The above code looks correct so you are good to go! (remember that to format your code on the forum, you can use the </> button instead of the quote one)