Can you see the contents of the custom field when you open the entity on which you placed the field? In that case it must be a permission issue. Do the users concerned have rights on saved searches (through their roles!), and do they have rights to the content presented in the custom field (through their roles)?

This covers it all I think: https://netsuite.custhelp.com/app/answers/detail/a_id/9425/kw/marketing%20emailing

I am relatively new as well, but an assembly requires a bill of materials. We have it on the assembly item under manufacturing tab. Maybe it’s different for you, we use manufacturing and advanced bill of material.  Bills of material are under Lists->Supply Chain->Bills of material in our setup.