Hi b3nelson and welcome to the forum.
The first question involves setting up a relationship between the two tables, go to the relationship graph in Define Database and create a join between your Main table and a MATERIALS and link these two fields
Material Number --=-- _UniqueID
Once that is done to list all related records you just need to place a portal on your layout using the portal tool and select the fields you wish to display.
With regards to your second question, you need to setup a script to achieve this. First create you print layout and then go 'Scripts > Manage Scripts...' and click '+New' bottom left.
And using the list of script steps on the left do the following:
Go to Layout [ PrintLayout ]
Print Setup [ ] Setup as your require, portrait landscape stc.
Print [ Current Record ] and again explore the options to suite your needs.
Go to Layout [ Original Layout ]
This will print the form and then return the user to where they started. If you want them to preview the form first you can add a Pause [ Indefinately ] step before the Print step, this will then print when the user hits 'Continue' or the enter key.
I hope this helps.