Cost price and inventory report how?

[SKIPPYINSPACE]

If I add a cost price to the simple product. (I'm taking cost and not wholesale price)

1. does it affect anything the customer sees on the front end
2. Does it affect the price the customer sees and buys
3. I take it there is a report then I can run which would show a stock valuation based on cost price
4. Is there a report that could produce a open / closing stock valuation over a 12 month period or should I be using my accounts software for that
5. Based on this I also assume that I can run a stock report based retail value
6. If these reports exist how do I run them

Thanks for your help

Ian