Let's tackle these one at a time.
Have another file upload that is supposed to add a new foreign key record to a child table, plus add a pdf file to the images directory, but doesn't do either. 
I only see one insert on the page. How is it supposed to add a new foreign key? What child table? Where does the pdf file come from? What file upload field are you referring to? I need a lot more information in understand what you are trying to do and why it doesn't work.
In addition, I have two checkboxes in the same form that don't add the appropriate foreign key records to their respective child tables either.
I don't see any code on the page that would insert based on these fields. Is this form just used for insert? It seems like you would need insert server behaviors for both of them.
Lastly, though the new product information is added correctly to the products Db, it doesn't update any of the child tables that are related.
You are going to need to add Insert Record Server behaviors for each table and row you expect to insert into. Maybe multiple insert server behaviors if you are using a repeated field like the checkboxes.
If you need help working on this, then the best option is to use premier support. I can help you debug issues you run into here, but if you want a tutorial on how to do something this isn't an efficient method. I really need to show you in a screen sharing session during premier support.
