I only ever get a max of 15kbps from manako too. I put it down to the long distance between Germany and Aus.
Plus the fact that he's one of only two people that seed nearly everything that's on the tracker doesn't help things much. At least you'll get it in the end, but patience is the key...
The deletion (or hiding for that matter) of threads has never been doable for the user. Editing, however, is a "new" (as in, didn't exist when the forum started) feature. But you can only edit your post within the first 24 hours. After that, it's going to stay here until the forum gets deleted/corrupted/lost/goes offline/etc. So, if you don't want your comments to be viewable for all time, be sure you post your message the way you want it posted (or not all?) the first time. Mouser X over and out.