Sellers can't leave negative (or neutral) feedback for buyers because too many sellers were using the threat of negative retaliation to discourage less than positive feedback from buyers no matter how warranted it was. And then if the threat wasn't enough, they would leave a scathing negative feedback for the buyer and seek a "mutual withdrawal." Since accurate and honest feedback for the seller is so much more important than for the buyer (all buyers have the ability to examine the seller's feedback profile before anything happens, while the seller is seldom able to do so and there are issues with taking action after the fact) eBay did away with negative and neutral feedback for buyers in 2008 and banned getting around that by leaving a negative comment on a positive rating.
On the other hand the Buyer Requirement that blocks those with 2 or more strikes in the past 12 months (or the more lenient settings available) acts automatically to block bids, offer, and BINs from serial deadbeats (IF their sellers used the proper unpaid item process) and so is far more effective than expecting to be able to react to feedback.
You have one or two (never can remember which) to change the duration of an auction (assuming no bids before then), and that's it. You can end the auction manually early after that (except you can't in the last 12 hours except to sell to the then high bidder at the then "current bid" amount unless there has ever been a bid). As you found out, there is a fee for ending early without a winner if there has ever been a bid (to deter sellers from doing so to avoid Reserve Fees to set the Starting Price at less than they were willing to sell for; you get one freebie per calendar year to allow for the very occasional legitimate reason to do so).
