Do customers have the ability to order samples packs from our print store and if so are the sample packs free?

Yes, customers are able to request sample packs directly off of your storefront. 

Once the request is made you will receive an email notification regarding the request.

You would need to manually order the samples through https://trade.4over.com/products/sample-request/ then send it to your customer since you are unable to push a sample request through to 4over from the admin.