For the uninitiated,
Speaking from the Oman side of UAE, we have a local agreement to sequence northern UAE traffic via two entry points, giving our friends across the border 10 miles between any two aircraft with no closing speed. How we arrange that is entirely up to us and does not take into consideration any future considerations/STARS/requirements that the UAE centre may have. Hence, we'll speed/slow people up willy-nilly to achieve that flow and we can sometimes have up to 15 aircraft all lined up, with another 15-20 on the way. We know it's not ideal to have you varying your speeds and flying non-optimum descent profiles but we are still a little in the dinosaur age when it comes to developing better ways of doing business. It can get very exciting because it is still old-fashioned, manual ATC.
With respect to asking for opposite runways, I, too, have had people asking for the wrong runway and they've only been able to make that request in a nanosecond where there wasn't a steady patter on the freq. Unless you really know that there's nothing going on at your destination, please don't ask. It just takes up precious thinking time.
Remember, too, that you may only be hearing 20-30% of what we're actually doing, even when we're busy on the freq.
Safe flying