Product Record Creation

Hi,

I am in the middle of creating product records for my stock and having the following questions.

What does cost price box refer to in a product record? In my case, the stock was imported. Would that be the unit cost of the stock INCLUDING import tax and duties plus carrier charges in this case?  

Will the stock be adjusted automatically by the software when a sale or purchase of stock is registered against the 5000 or 4000 nominal code ranges or do I have to adjust it manually in Products and Services Module? I am using Sage Instant 2015. 

Will the software facility enable me to register other items than products for sale in Products and Services Module. i.e. mailing boxes or product packages as I would like to track quantities of those as well? 

Any advice is appreciated. 

Thank you