In regards to GS1 barcode - what size DB field are used? In regards to GS1 barcode - what size DB field is used or is the entire GS1 typically not stored in database, but rather processed in the application layer and stored in the database as a collection of the component parts?  

The length of the GS1 in its entirety is the subject of this question
As the maximum number of characters in a single symbol is 48 and the Technical Spec for aggregators (http://www.gs1.org/sites/default/files/docs/gs1-source/TSD_v1_1_Technical_Implementation_Guide_for_Aggregators.pdf) indicates the file can come in as UTF-8. UTF-16, or UTF-32, the safest bet would be

nvarchar(48)