On shipping, at times, I have charged a high shipping charge, stated right up front, and then posted the item at one cent. I figure people can do math, and of course, I save eBay fees. Stated this way, I have no problem with relatively high shipping charges. I have also sold items (rarely) with free shipping.
I agree, the feedback retaliation is awful. So I am hesitant to leave negative feedback as a buyer, and I am hesitant to leave positive as a seller before receiving the same. To me, the fair way is if you are unhappy with an item, email first, let the seller take care of it. And if they do not, then go ahead and flame them.