No you can't offer the bidders a 'second chance offer' on an auction that did not end with a winning bidder. Ebay accesses that at 'fee avoidance' and most likely you will get suspended if they find out. You can only make 'second chance offers' to the bidders that made unsucessful bids on you auction that closed with a winner. In addition when making a second chance offer you have to sell the item to them at their highest bid,,,that is to say that if their last bid was $10.99, that is the price that you can offer it to them if you are willing to accept that bid..($10.99)
Putting a reserve in a listing can help you or hurt you. Alot of bidders don't like to waste their time putting in a bid if they don't really know what kind of price you are expecting. Sometimes expecially on low ticket items, it's just better to figure out what is the least amount that you would want to accept for the item and start the bidding at that price..That amount should have all of your fees plus at least a small profit figured into it so that you are going to be ahead at the first bid..
If you have an item that you know is going to do well and get alot of bids then a reserve can help you by allowing you to start the bidding at a low price, thus saving on listing fees and not to come up short on the final price in case you do not get as many bids as you expected..
I myself never use reserve auctions and would suggest that you not on small ticket items..