Marco,
Edit your Kitchen Order print job, and change the Product Group under Print Mapping to just Snacks (or whatever the item group is). If you have many groups for the kitchen, what I have setup in the past is a second kitchen order template and call it Beverages Orders. I added this to the Kitchen orders print job, and selected only the product groups not going to the kitchen, and set the receipt printer for the job. See attached pic.
For your second question. I would use Ticket Tags, and assign the pager that way, and add
<C00>Pager: {TICKETTAG:Pager}
to your kitchen printer template to show as below.
Kitchen Order
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Date: 5/07/2013 Time:12:29 PM
Table No: Ticket No: RT90
Pager: 2
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Mains
1x Confit Duck
1x Chicken Breast
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To speed up adding the Pager numbers to the Ticket Tag (80 is a lot to add at once), enable Free Tagging & Save Free Tags in the Ticket Tag options for the Pager - this allows you to enter a pager number and save it for later, or you can just use Free Tagging every time.