If you both want to complete the transaction through eBay, you will have to make a new listing for the agreed amount.
I would suggest that you use your customer's name as the title, since no one is likely to Search on that and scoop it out from under him.
Fees would be the same as they were for the auction, but you might want to look into the cost of a Fixed Price listing instead.
http://pages.ebay.ca/help/sell/insertion-fee.html
2. - I am requesting $US - how do I determine the conversion to $C.
When you make the new listing, use the Advanced Sell Your Item Form . My own templates have been set in stone for years and I don't know how a new seller Finds this. It may be a dropdown from SELL.
The Advanced Form allows you to choose USD or CDN funds.
Or go to Paypal and use their Send Money form. That allows your choice of currencies.