For your first question could you please try to set the RowHeight property of the RadTileView - with it you set the height of all RadTileViewItems.
The problem in your second question occurs because the RadTileView have a build-in ScrollViewer and it catches the MouseWheelDown and MouseWheelUp events.
I'm not sure why the third problem occurs and we'll need some more time for further investigation.
For now I can advise you to try not to put the RadTileView inside a ScrollVIewer and use its build-in one if posible.
I've attached a sample project and if you have further questions feel free to ask.
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