I am not able to reproduce the reordering issue. I've attached a video and an application. If you run the application, are you able to reorder the items as shown on the video? Probably you've set some properties to RadTileView and RadTileViewItem which might be preventing you from reordering the items.
As for question #2, currently this scenario is not supported. RadTileView does not support reordering its items when they are minimized. However, I've added this feature request in our public issue tracking system
under the name "TileView: Enable reordering of TileViewItems when in Minimized mode
" and it will be available for tracking and voting tomorrow the latest. If this feature request gathers enough popularity we will definitely implement it.
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system and vote to affect the priority of the items.