Too late in the hour for me to download your file and start looking at it. Best approach is to either link to the spreadsheet as you would a table OR import or use transferspreadsheet function to put 'raw' data into Access in a staging table. Then append to the final/destination table in Access, which has all the settings you need (primary key, index(es), data types and so on). If 123 comes across from Excel as text, when you append it to the final table, it will become a number type if that's how you define the field. You prevent the duplication of records by defining a unique index, which could be a single field or if need be, 2 or more fields.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.